Timer

Hello I am trying to make a timer that counts upward but its not working here’s the error message Arduino: 1.8.8 (Windows Store 1.8.19.0) (Windows 10), Board: "Arduino/Genuino Uno"
sketch_feb26a:9:22: error: TimerOne.h: No such file or directory
compilation terminated.
exit status 1
TimerOne.h: No such file or directory
This report would have more information with
"Show verbose output during compilation"
option enabled in File → Preferences.
and heres the whole code and link to the video

the board im using is a sainsmart Arduino/geniuno UNO

#include <TimerOne.h>
//the pins of 4-digit 7-segment display attach to pin2-13 respectively
int a = 2;
int b = 3;
int c = 4;
int d = 5;
int e = 6;
int f = 7;
int g = 8;
int p = 9;
int d4 = 10;
int d3 = 11;
int d2 = 12;
int d1 = 13;
long n = 0;// n represents the value displayed on the LED display. For example, when n=0, 0000 is displayed. The maximum value is 9999.
int x = 100;
int del = 5;//Set del as 5; the value is the degree of fine tuning for the clock
int count = 0;//Set count=0. Here count is a count value that increases by 1 every 0.1 second, which means 1 second is counted when the value is 10
void setup()
{
** //set all the pins of the LED display as output**
** pinMode(d1, OUTPUT);**
** pinMode(d2, OUTPUT);**
** pinMode(d3, OUTPUT);**
** pinMode(d4, OUTPUT);**
** pinMode(a, OUTPUT);**
** pinMode(b, OUTPUT);**
** pinMode(c, OUTPUT);**
** pinMode(d, OUTPUT);**
** pinMode(e, OUTPUT);**
** pinMode(f, OUTPUT);**
** pinMode(g, OUTPUT);**
** pinMode(p, OUTPUT);**
** Timer1.initialize(100000); // set a timer of length 100000 microseconds (or 0.1 sec - or 10Hz => the led will blink 5 times, 5 cycles of on-and-off, per second)**
** Timer1.attachInterrupt( add ); // attach the service routine here**
}
/***************************************/
void loop()
{
** clearLEDs();//clear the 7-segment display screen**
** pickDigit(0);//Light up 7-segment display d1**
** pickNumber((n/1000));// get the value of thousand**
** delay(del);//delay 5ms**
** clearLEDs();//clear the 7-segment display screen**
** pickDigit(1);//Light up 7-segment display d2**
** pickNumber((n%1000)/100);// get the value of hundred**
** delay(del);//delay 5ms**
** clearLEDs();//clear the 7-segment display screen**
** pickDigit(2);//Light up 7-segment display d3**
** pickNumber(n%100/10);//get the value of ten**
** delay(del);//delay 5ms**
** clearLEDs();//clear the 7-segment display screen**
** pickDigit(3);//Light up 7-segment display d4**
** pickNumber(n%10);//Get the value of single digit**
** delay(del);//delay 5ms**
}
/**************************************/
void pickDigit(int x) //light up a 7-segment display
{
** //The 7-segment LED display is a common-cathode one. So also use digitalWrite to set d1 as high and the LED will go out**
** digitalWrite(d1, HIGH);**
** digitalWrite(d2, HIGH);**
** digitalWrite(d3, HIGH);**
** digitalWrite(d4, HIGH);**
** switch(x)**
** {**
** case 0:**
** digitalWrite(d1, LOW);//Light d1 up**
** break;**
** case 1:**
** digitalWrite(d2, LOW); //Light d2 up**
** break;**
** case 2:**
** digitalWrite(d3, LOW); //Light d3 up**
** break;**
** default:**
** digitalWrite(d4, LOW); //Light d4 up**
** break;**
** }**
}
//The function is to control the 7-segment LED display to display numbers. Here x is the number to be displayed. It is an integer from 0 to 9
void pickNumber(int x)
{
** switch(x)**
** {**
** default:**
** zero();**
** break;**
** case 1:**
** one();**
** break;**
** case 2:**
** two();**
** break;**
** case 3:**
** three();**
** break;**
** case 4:**
** four();**
** break;**
** case 5:**
** five();**
** break;**
** case 6:**
** six();**
** break;**
** case 7:**
** seven();**
** break;**
** case 8:**
** eight();**
** break;**
** case 9:**
** nine();**
** break;**
** }**
}
void clearLEDs() //clear the 7-segment display screen
{
** digitalWrite(a, LOW);**
** digitalWrite(b, LOW);**
** digitalWrite(c, LOW);**
** digitalWrite(d, LOW);**
** digitalWrite(e, LOW);**
** digitalWrite(f, LOW);**
** digitalWrite(g, LOW);**
** digitalWrite(p, LOW);**
}
void zero() //the 7-segment led display 0
{
** digitalWrite(a, HIGH);**
** digitalWrite(b, HIGH);**
** digitalWrite(c, HIGH);**
** digitalWrite(d, HIGH);**
** digitalWrite(e, HIGH);**
** digitalWrite(f, HIGH);**
** digitalWrite(g, LOW);**
}
void one() //the 7-segment led display 1
{
** digitalWrite(a, LOW);**
** digitalWrite(b, HIGH);**
** digitalWrite(c, HIGH);**
** digitalWrite(d, LOW);**
** digitalWrite(e, LOW);**
** digitalWrite(f, LOW);**
** digitalWrite(g, LOW);**
}
void two() //the 7-segment led display 2
{
** digitalWrite(a, HIGH);**
** digitalWrite(b, HIGH);**
** digitalWrite(c, LOW);**
** digitalWrite(d, HIGH);**
** digitalWrite(e, HIGH);**
** digitalWrite(f, LOW);**
** digitalWrite(g, HIGH);**
}
void three() //the 7-segment led display 3
{
** digitalWrite(a, HIGH);**
** digitalWrite(b, HIGH);**
** digitalWrite(c, HIGH);**
** digitalWrite(d, HIGH);**
** digitalWrite(e, LOW);**
** digitalWrite(f, LOW);**
** digitalWrite(g, HIGH);**
}
void four() //the 7-segment led display 4
{
** digitalWrite(a, LOW);**
** digitalWrite(b, HIGH);**
** digitalWrite(c, HIGH);**
** digitalWrite(d, LOW);**
** digitalWrite(e, LOW);**
** digitalWrite(f, HIGH);**
** digitalWrite(g, HIGH);**
}
void five() //the 7-segment led display 5
{
** digitalWrite(a, HIGH);**
** digitalWrite(b, LOW);**
** digitalWrite(c, HIGH);**
** digitalWrite(d, HIGH);**
** digitalWrite(e, LOW);**
** digitalWrite(f, HIGH);**
** digitalWrite(g, HIGH);**
}
void six() //the 7-segment led display 6
{
** digitalWrite(a, HIGH);**
** digitalWrite(b, LOW);**
** digitalWrite(c, HIGH);**
** digitalWrite(d, HIGH);**
** digitalWrite(e, HIGH);**
** digitalWrite(f, HIGH);**
** digitalWrite(g, HIGH);**
}
void seven() //the 7-segment led display 7
{
** digitalWrite(a, HIGH);**
** digitalWrite(b, HIGH);**
** digitalWrite(c, HIGH);**
** digitalWrite(d, LOW);**
** digitalWrite(e, LOW);**
** digitalWrite(f, LOW);**
** digitalWrite(g, LOW);**
}
void eight() //the 7-segment led display 8
{
** digitalWrite(a, HIGH);**
** digitalWrite(b, HIGH);**
** digitalWrite(c, HIGH);**
** digitalWrite(d, HIGH);**
** digitalWrite(e, HIGH);**
** digitalWrite(f, HIGH);**
** digitalWrite(g, HIGH);**
}
void nine() //the 7-segment led display 9
{
** digitalWrite(a, HIGH);**
** digitalWrite(b, HIGH);**
** digitalWrite(c, HIGH);**
** digitalWrite(d, HIGH);**
** digitalWrite(e, LOW);**
** digitalWrite(f, HIGH);**
** digitalWrite(g, HIGH);**
}
/*******************************************/
void add()
{
** // Toggle LED**
** count ++;**
** if(count == 10)**
** {**
** count = 0;**
** n++;**
** if(n == 10000)**
** {**
** n = 0;**
** }**
** }**
}

Did you install the TimerOne library?

Did you install a TimerOne library?

Did you install the TimerOne library?

In the Arduino software (IDE), goto (click):

Sketch>Include Library>Manage Libraries

After clicking "Manage Libraries", a new form will pop up - type TimerOne into the search bar; the form will filter; click the second entry. After clicking the second entry, a button will be visible labeled as install. Click the install button and you're on your way.

thank you