So for github you need to clone the repo into your own. Then add your repo as a remote to the pgjdbc repo. Then you can push to your repo on a different branch and create pull requests.
I have updated the patch to also include proper handling of the new identity columns. getColumns() now returns YES for IS_AUTOINCREMENT
I tried to find out how to do this via Github, but the Github manual only says I need to push my commit to a branch, but even if I create a local tracking branch I can't push that, so I am a bit lost (never worked with Github before and git itself doesn't like me anyway)
