WebAssist use to have a tutorial on saving the cart contents to recordsets and then developing the ability for a returning customer to access their uncompleted order. It seems to no longer be on their site.
It's not a terribly complex bit of functionality to develop, but is probably a bit above a newbe.
To give you starting points... you would utilize the STORE CART SUMMARY IN DATABASE and STORE CART DETAILS IN DATABASE server behaviors for eCart to save the cart details to recordsets.
You would use a SQL JOIN to combine the orders and orderdetails recordsets and filter them with a unique value (such as customerid) to bring up the cart details on a return visit from the customer.
There's more to it, but that's the basic way to get there.