How to change the program code using arduino decimila instead of arduino uno

Using this circuit. http://www.makershed.com/Pulse_Sensor_for_Arduino_5_Volt_p/mkre1.htm

Here is the link of the sample code: http://code.google.com/p/pulse-sensor/downloads/list

Which one should we chose and how to change it. Please we need help. Thanks in advance.

Which one should we chose

For what?

and how to change it.

Using a text editor usually works.

Your Arduino is a 5v version and in that way is compatible with the Uno.