I'm still not sure what you're asking- do you want to create a sketch that interacts with git in some way? Or do you want to modify the Processing IDE itself to support git features?
I doubt it's exactly trivial to do either one. You can probably find a Java library that supports interacting with a git repository.
Answers
What specifically would you like to do?
To save the code of projects.
From inside a Processing sketch? Or just using standard git? If the latter, I suggest you start here: http://git-scm.com/book/en/Getting-Started
I mean the first, is any plugin or something else to connecting processing with git?
I'm still not sure what you're asking- do you want to create a sketch that interacts with git in some way? Or do you want to modify the Processing IDE itself to support git features?
I doubt it's exactly trivial to do either one. You can probably find a Java library that supports interacting with a git repository.