Github pull request without old commits

I have forked project at github. I make one commit and pull request it. This commit was approved. Then i make second com开发者_运维技巧mit and pull request it too. But in pull request there were 2 commits: my second commit and old commit which was approved. How can i sync my repository and main repository?

Merge back from the upstream repository, or create the new pull request on a new branch.

Or rebase on top of upstream:

git remote add upstream (url-for-upstream-repository)
git fetch upstream
git rebase upstream/master
git push -f origin
(do new pull request on website)