Rebecca, do you know what cart she/you want to use?
ETA: Okay, I think you mean 1shopping cart.

Have you visited their website?
http://www.1shoppingcart.com/shopping-cart-software.asp She would need a payment gateway with this and they do charge for their service, as will 1shoppingcart, so I would make sure she understood all the charges involved for processing payments. Or perhaps
http://www.1shoppingcart.com/shoppin...nt-account.asp would work better since it has Power Pay and authorize.net (a payment gateway) integrated.
If you have experience with website coding (HTML) and inserting codes that are generated you should do fine.