To get started with Android/CyanogenMod, you'll need to get familiar with Git and Repo.
To initialize your local repository using the CyanogenMod trees, use a command like this:
repo init -u git://github.com/SamsungBCM-Cyanogenmod/android.git -b cm-10.2
Then to sync up:
repo sync
Please see the CyanogenMod Wiki for building instructions.
Enter this command:
./build.sh
Then choose the device/devices you want to compile for:
1 = Galaxy S2 Plus NFC (s2vep)
2 = Galaxy S2 Plus (s2ve)
3 = Galaxy Grand Duos (baffin)
12 = Galaxy S2 Plus NFC (s2vep) + Galaxy S2 Plus (s2ve)
13 = Galaxy S2 Plus NFC (s2vep) + Galaxy Grand Duos (baffin)
23 = Galaxy S2 Plus (s2ve) + Galaxy Grand Duos (baffin)
123 = Galaxy S2 Plus NFC (s2vep) + Galaxy S2 Plus (s2ve) + Galaxy Grand Duos (baffin)