How can i get ardupilot code

ArduCopter Copter 3.2
1

i am using apm2. 6 copter ac3. 2.1, since ardupilot group is open source, so how can i access and get the prgram code for my firmware

2

Ardupilot source code is here: https://github.com/ArduPilot/ardupilot