Two good options for uploading your completed movie to the web are Castpost and You Tube. I have no idea which is better but at the moment Castpost is full and not taking any new members, therefore You Tube is probably your best bet!
HERE IS THE PROCESS I FOLLOWED:
Gosh, sounds more complicated when you write it out like that doesn't it! I haven't much experience with full-on editing in imovie so that part of the process took me w wee while, it wasn't a perfect job but we all learn from our first attempts don't we!
NOTE: If your internet connection is slow or dial up we suggest you let the video play once sluggishly (right until the end) while you have a cuppa. It will then be easier to view the second time it has loaded.