Here is a link to a post from last year on setting up Google Docs. There have been one or two changes since then but I think it still works pretty much as described.
Unless asked otherwise, please share any homework tasks with me via Google Docs. If you have any problems with it, please let me know and I’ll see if I can help you to get it sorted.
How to set up & share with Google Docs: http://mcfilm.posterous.com/instructions-for-setting-up-sharing-google-do