I'm adding categories to my main site under products. They

I'm adding categories to my main site under products. They are not transferring to my test shops categories. (could be because I've already create the shop before the new categories. or should I make the category layout some other place in my site)?

I'm trying to figure out the easiest way to lay out categories for a shopping site.

Also how can I change it so my users cannot add their own categories?