Git Switching branch

Question

There is somthing I don\'t get yet with git. It is branch. So let say that I have a local repository A which I clone from a remote one B. So now

Answer 1

In two lines:
git fetch C
git checkout -b myCopy -t C/stable-branch

myCopy is now a local branch of C/stable-branch, and is tracking it, so you can do git push and git pull without a refspec.

Answer 2

git fetch C
git checkout C/stable-branch
git checkout -b myCopy

Then myCopy is a local (copied) branch of C's stable one.