making a battery bar on touchshield slide

I'm trying to make a battery bar for my project so you can monitor the battery voltage and know when it is needs charging. Im using the touchshield slide http://www.liquidware.com/shop/show/TSL/TouchShield+Slide+ which is programmed seperately from the arduino. I already have the code for getting the voltage and send it to the touch shield:

#include 
#define RXpin 3            //touchshield slide pins
#define TXpin 2
SoftwareSerial touchSerial = SoftwareSerial(RXpin, TXpin);
void setup(){
touchSerial.begin(9600);
}

void loop(){
  
float volts = (analogRead(A0) * 5.0) / 1024;
delay(1000);
touchSerial.println(volts);
}

now i need help to make the bar on the screen to decrease and increase with the voltage..like a regular battery bar you see on a phone

im using this battery http://www.adafruit.com/products/328 and this charger http://www.adafruit.com/products/259