As you have found, FrontPage does not have this frames template built in. Its nearest equivalent is the Header, Footer and Contents frames template, which gives you a top, bottom, left and main window.
It's simple enough to create your own frameset though.
One point worth mentioning here before you go charging on in: if you have the top, bottom, left and right sections of your page occupied, the centre window may be a little small and cramped to fit much in for an e-shop. Just a thought.
There's a nice walk through click here on creating or editing a frameset to your own requirements, but effectively if you choose the Header, Footer and Contents frame template from the File, New, Page menu, click in the main frame window to select it, then click on Frame (top toolbar) then select split. Choose columns and not rows, then drag the frame elements to the size you want.
If you come unstuck, post again, but it's really very simple and the above link explains it far more visually than I have in here.
Hope this helps.