You can browse the category hierarchy by clicking on one of the top-level categories from the home page, or clicking on "Browse" in the left-hand menu.
When you click on a category you will see a list of all the sub-categories of that category, and a list of all items that are in that category. If there are more items than can be shown on one page then you can page through them.
You can click on a subcategory to navigate further down the category tree, or click on the breadcrumb trail to move back up.
Click on a thumbnail to view the item details.