The first time you read the readme/source it might look very hard. Just read the readme a few times and you'll understand how the bot itself works. After that you should reading cpp files such as bot.cpp and bot_combat.cpp and things will start to make even more sence.
Now you can start with modifying small things(add mod-specific entities in h_export, change the weapon table in bot_combat etc).
Ofcourse if you have any problems you can ask them here
