2012-06-11 2:51 pm EST
There are many ecommerce programs out there and each one is different. You do want to find the ones that allow you sell digital products. Ecommerce programs such as ZenCart, Open Cart, and PrestaShop allow this. I am not familiar with all of the ecommerce programs, but you can visit the sites for each program to see which one will have the best look and feel for you.
ZenCart can be installed via the Fantastico tool found in your cpanel.
Fantastico does not have an install program for Open Cart or PrestaShop and they will need manual installation. The Prestashop instructions are found here. And the Open Cart instructions are here.
I hope this answers your question. If you have any more questions or information specific to the issue please leave a comment below so we can further assist you.