There's no action on your form to post emails for newsletters. Search google for 'post form action' or 'processing html forms'. You have no doctype declaration in your html which may screw up the way your website works for some people. You have used a LOT of sliced up graphics, this could be a reason why pages take ages to load, you need to rebuild in html rather than import a graphic to be your main page. Some of which don't show properly in firefox, leaving big holes or pixel gaps in your design. I don't think contacts us is correct grammar? Your t-shirt colours when rolled over aren't consistent, the t-shirt bounces around all over the place. You should consider re-designing your site using divs, and removing all those unnecessary spacer gifs and tables (which you'll find most experienced web designers hate!). I appreciate you don't have a clue what you are doing and to be honest it shows. Either get more experience and do some tutorials on web design/css/graphic design theory - before trying to tackle this anymore, or get someone else to build this website for you.
