Yeah ok, this is an easy topic but people still Google it, and take a moment to see the number of posts on Stackoverflow.
First check your branch:
$ git branch
Your current branch will show with an asterisk (*) next the name.
Next, update your local branch with the remote branch. Replace with the name pf the branch you want to pull:
$ git pull origin <branch>
You are good to go. You can push your code as needed:
$ git push origin <branch>