Setting up a non-profit event site with online registration. Setting up a way to register by purchasing tickets and extras, online.

Have used in past and am trying today to use ECWID for the 'shopping cart'. It seems Ecwid changed the screen layout options in the last year or so, and is more visual for selecting products. Not been able to get it to format or auto-flow thru items.

Would like people to 'register' with name and such and pick which type type they want. Then 'advance' to ask if they want to buy a shirt and what size. And then advance to select extra fare option 1, then advance to extra fare option 2. Basically, to lead them thru the options. Today they have to manually go in and pick one, go back to 'shop more' for the next, go back and forth...
Think last event, I did 'separate pages' and had people advance from page to page with one option on each. But if they hit <Back> it got messy.

Anyone using Ecwid and made it work as I mentioned?
OR... using another 'free' Shopping Cart service that fits what I am looking for?


thanks in advance,
Frolin