I tried looking through all my internet favourites but most of the tutorials on there are for bags and accessories rather than clothes.
This is a link to a screenprinting tutorial, it may help: http://community.livejournal.com/craftgrrl/3674467.html
Posts by Shivi
they have a t-shirt bag tute on Martha Stewart- it looks quite simple:
http://www.marthastewart.com/article/good-thing-t-shirt-bag?autonomy_kw=t-shirt%20bags&rsc=header_1
If you haven't had much experience I wouldn't reccomend you do this first off, it's quite intricate, start on some more basic items maybe using a pattern.
no offence Tina but don't you have to move in any dress you wear?
seriously, how does that dress even stay up! lol