Issues creating a new library

HI to all. i am design a library to use a sensor, but when i compile my example i had a lot of errors. the source code its the next:

the header file.

#ifndef Ultrasonico_h
#define Ultrasonico_h
#include "Arduino.h"

class Ultrasonico
{
      public:
             Ultrasonico(int trigPin, int echoPin);
             long Duration();
             long Distancia();
             void Begin();
      
      private:
              int _trigPin;
              int _echoPin;
};

#endif

the .cpp file

#include "Arduino.h"
#include "Ultrasonico.h"

Ultrasonico::Ultrasonico(int trigPin, int echoPin)
{
                             _trigPin=trigPin;
                             _echoPin=echoPin;
}

Ultrasonico::Begin(){
                     Serial.begin(9600);
                     pinMode(_trigPin,OUTPUT);
                     pinMode(_echoPin,INPUT);
                     digitalWrite(_trigPin,LOW);
                     }
Ultrasonico::Duration(){
                     long duration;
                     digitalWrite(_trigPin,HIGH);
                     delayMicroseconds(10);
                     digitalWrite(_trigPin,LOW);
                     duration=pulseIn(_echoPin,HIGH);
                     return duration;
                     }

Ultrasonico::Distancia(){
                           long cm;
                           Duration();
                           cm=duration/58;
                           }

the ide give me this errors:

C:\Documents and Settings\Owner\My Documents\Arduino\libraries\Ultrasonico\Ultrasonico.cpp:10: error: ISO C++ forbids declaration of 'Begin' with no type C:\Documents and Settings\Owner\My Documents\Arduino\libraries\Ultrasonico\Ultrasonico.cpp:10: error: prototype for 'int Ultrasonico::Begin()' does not match any in class 'Ultrasonico' C:\Documents and Settings\Owner\My Documents\Arduino\libraries\Ultrasonico\/Ultrasonico.h:17: error: candidate is: void Ultrasonico::Begin() C:\Documents and Settings\Owner\My Documents\Arduino\libraries\Ultrasonico\Ultrasonico.cpp:16: error: ISO C++ forbids declaration of 'Duration' with no type C:\Documents and Settings\Owner\My Documents\Arduino\libraries\Ultrasonico\Ultrasonico.cpp:16: error: prototype for 'int Ultrasonico::Duration()' does not match any in class 'Ultrasonico' C:\Documents and Settings\Owner\My Documents\Arduino\libraries\Ultrasonico\/Ultrasonico.h:15: error: candidate is: long int Ultrasonico::Duration() C:\Documents and Settings\Owner\My Documents\Arduino\libraries\Ultrasonico\Ultrasonico.cpp:25: error: ISO C++ forbids declaration of 'Distancia' with no type C:\Documents and Settings\Owner\My Documents\Arduino\libraries\Ultrasonico\Ultrasonico.cpp:25: error: prototype for 'int Ultrasonico::Distancia()' does not match any in class 'Ultrasonico' C:\Documents and Settings\Owner\My Documents\Arduino\libraries\Ultrasonico\/Ultrasonico.h:16: error: candidate is: long int Ultrasonico::Distancia()

anybody can help me to solve this?

Ultrasonico::Duration(){

Should be

long Ultrasonico::Duration(){

Etc.

Thanks a lot.
my problems now are solved =D