It took me even longer to realise that when you load your master branch - you still need to pull changes from the original unforked repository (into your local repository) and then push them back up to your fork, AND then branch to make a change. For ages I was was getting unrelated diff changes even though I thought I had started on ���master���.
I���m hoping there will be a talk about all of this at Pharo Days. When you get it right its awesome - but when you take a mis-step its quite confusing until you realise what the pieces mean. (And I���m sure I still have the model wrong, but its fun learning more each day)