How to upload a file and get it reviewed:

1) git checkout branch_name origin/master
2) git checkout branch_name
3) Create your file
4) git add file_name
5) git commit -m "problem_name"
6) git push origin HEAD:branch_name
7) Open a new pull requests

After it gets reviewed:
1) Answer all questions in review comments.
2) git checkout branch_name
3) Edit your code based on review comments.
4) git add file_name
5) git commit -m "version x"
6) git push origin HEAD:branch_name