I have a cloned project from a master branch from remote repository remote_repo. I create a new branch and I commit to that branch. Other programmers pushed to remote_repo to the master branch.

I now need to rebase my local branch RB onto remote_repo's master branch.

How to do this? What commands to type to a terminal?

First fetch the new master from the upstream repository, then rebase your work branch on that:

git fetch origin            # Updates origin/master
git rebase origin/master    # Rebases current branch onto origin/master

Update: Please see Paul Draper's answer for a more concise way to do the same - recent Git versions provide a simpler way to do the equivalent of the above two commands.