First I accidentally sent my items to my inventory and thought that my items disappeared. Then the items wouldn't show in my shop except as a display item, only. How do I sell items in my user-shop?

One you put everything in your shop, you need to go into the shop to add the prices. You can add them to the shop through Quick stock (when you hover over commerce >> your shops >> [name of your shop here] (qs), the qs link will take you there. Put everything you want to sell in the shop. From there, there will be a link at the top to autoprice (because you have a gold account) and if you follow the buttons it will automatically put everything at the lowest available prices in the user shops (it has been a long time since I used this feature, but there used to be a way to select if you wanted something priced differently).

If you don't have a gold account (or this one expires, or you want to hand-price items lower than the current lowest), in the menu across the top of the shop, select "Edit Items" and from there you can input what you want the prices to be. Without the GA, you won't know what the current lowest price is without looking the item up.

Thanks for the info!