To add a category in K2 (also known as a section):
- Log into your Joomla administration area
- Highlight "components" in the top menu and then select "K2"
- The first tab highlighted will be "items" - select the next section over, which is "categories"
- Click "new" in the upper right hand corner to create a new category
- Enter the title of your new category
- Leave "Title alias (url)" blank
- If this category belongs to another parent category, select the appropriate category in the "parent category" list
- Click "save & close" in the upper right to create and save your new category