From what I understand, a lot of people who have download stores on UMD (and some who don't have download stores at all) didn't know that they can place a download store right on their site.
As you know, every UMD member already has a download store. All they have to do is upload files to it and get paid for the sales. But to put the store on your web site, I figure I'd mention the steps!
1) Go to your profile and click on the "Store & Sale Setup" link at the left.
2) Your stores are listed in boxes which also contain a red link that says "Embed store on your site." Click this link for the store you wish to embed (make sure the store is open).
3) You'll see a bunch of options and checkboxes to customize things how you want them. Then a button to save and get copy-n-paste code.
4) Click the Save button and you'll get the code to put onto your site. When you put it on your site, a full-blown store will appear with just your content in it, complete with a shopping cart. The checkout process still happens here at UMD when they are ready to buy.
And that's it! Hope this clears things up a little...
Messmaster
Stay messy, my friends.