This is probably a dumb question, but....
I have a drop down selection menu and an add to cart button. I want the link to change to whatever selected item so that the item shows up in the shopping cart. I've tried several different things but nothing seems to work... Probably something dumb that I've overlooked but I'm desperate for any help!

Set the selected attribute in the <option> tag you want to have selected. You will need a scripting language (server-side is easier) to do this for you. I usually use selected="selected" just because it works in all browsers I've tried, and is standards compliant.