How much would you charge?

I just created an xml-image-rotator using actionscript for a graphic designer and more actionscript-related work will be done later. I think the “best” way for compensation would be to charge him by hour? or is there a better way to do this?

and how much would be a fair fee for both of us?

I am a novice so I did spend a lot of time on it, but, it works perfectly to his specifications. Any feedback would be appreciated.