To add an item to your cart on Al Marwan, there are a few options available. If you're interested in a specific item listed for sale, you can click the "buy now" button on the listing to add it directly to your cart. Additionally, if you "make an offer" on a listing, that offer will also be added to your cart. Furthermore, if you apply for financing within a listing, it will automatically be added to your cart. Alternatively, if you want to save an item for future reference without purchasing it immediately, you can click the "heart" button on the listing to add it to your wishlist. This allows you to keep track of items you're interested in, even if they are not currently in your cart.