The basic gist of using ecart is:
- Create the product catalog pages.
- Create the eCart object
- Add the Add to Cart button behavior to the catalog pages
- Create a cart display page using the Cart Display Manager.
- Run the Checkout wizard to create the checkout pages.
The interfaces in eCart 5 may be slightly different than in eCart 6, but the basic functionality is the same.
If you have questions, your best bet is to ask them here. IF need be, I can call tomorrow afternoon, but asking questions here would be quickest.