When you have opened a shop, your uploaded models go into the shop.
You can manage the models from 'My Shop' or 'My Models'
On the model edit page, you will see a variety of shop related items.
The left side of the page deals with the model, the right side deals with availability and pricing.
Under the material selector (right side) you are able to select which materials are publically visable and how much mark up you can add to each.
The model description box can be formatted with html tags.