Download the latest version of git from here: http://git-scm.com

Graphical front ends can be found here: http://git-scm.com/download/gui/mac

Read more about git here (the first 3 chapters are enough to get going): http://git-scm.com/book/en/Git-Basics-Recording-Changes-to-the-Repository

Here's a git cheatsheet: http://cloud.github.com/downloads/AlexZeitler/gitcheatsheet/gitcheatshee...

Put the following in a file called .gitignore in your home directory:

*.[oa]
*.mxo
*.mxe
*.class
*.objinfo.txt
*.tar.gz
*.zip
*.def
*~
\#\*\#
xcuserdata
.DS_Store
build
build-gcc
*.pbxuser
*.mode1v3
*.mode2v3
*.perspectivev3
!default.pbxuser
!default.mode1v3
!default.mode2v3
!default.perspectivev3
!xcshareddata