I was exactly where you were two months ago, and posted a summary of the main things I learned. You may want to take a look...
http://forum.x-cart.com/viewtopic.php?t=9123
X-Cart is really meant to be used for all your product pages, but it is possible to just use the cart portion. As a last resort you could create your product pages outside of x-cart, put an add to cart gif next to each product, and link that gif with the direct "add to cart" HTML code.*
* You can get the direct HTML code by clicking modify product, then "generate HTML links". You have to first enter your product info.
This really is a last resort though. I did this with my first cart (since I was short on time and had really complex layouts on the product pages).
HTH,
:Stacey