Submitting changes back to the baseline

Forgive my ignorance here, I haven't really been involved in any Open Source projects before.

I was wondering what the correct process is for submitting code back into the project. I've made a couple of changes here and there, some of which are definately only useful for me, and some of which I would consider worthy of baseline inclusion.

Do I just post them to the forum? Should I create and submit a patch?

Thanks
Ben