Suppose you want to work with a git repository called test.git, here are the basic tasks you might be interested:
Clone A Repository
In Subversion, it is usually called a checkout, but for git, you do cloning:
git clone firstname.lastname@example.org:test.git
Now you should have a directory test created which has all the files and history ever recorded for this repository.
Add a new file and commit the changes
Say you want to add a new file into the repo.
git add mynew.cpp git commit -am "my new file"