$ git branch my_feature # Creating the branch
$ git checkout my_feature # Changing the codebase so that we're on that branch now
$ git checkout -b my_feature # This does the two previous operations in one ;)
$ git add file1 file2
$ git commit -m "Meaningful commit message" # We didn't just commit this on the master branch like last time, but on the my_feature one
$ git add .
$ git commit -m "Other meaningful commit message"
$ git push origin my_feature # Notice: we're not pushing master anymore, you just create a new remote branch