Open the forked Git repository me/foobar.
Click on Compare:
You will get the notification:
There isn’t anything to compare.
someone:master is up to date with all commits from me:master. Try switching the base for your comparison.
Click on switching the base on this page:
Then you get to see all the commits made to someone/foobar after the day you forked it.
Click on Create pull request:
Give the pull request a title and maybe a description and click Create pull request.
On the next page, scroll to the bottom of the page and click Merge pull request and Confirm merge.
Your Git repository me/foobar will be updated.
Edit: rebase options are shown here:
