To add Categories for your website, please follow the below steps.
On Dashboard Click on Manage websites Menu and then click on Categories Menu in the left sidebar.
Once the Categories page is loaded click on Add Category button at top right. Please refer below screenshot.
Once the form is loaded. the form have 2 sections, the left section lists all the campaigns created and the right site you will see options like category name and selected campaigns, etc.
Once you provide all the details hit save category to save, the page will load with table where you will be able to see the saved categories for your different websites.
Please feel free to reach to support desk if any help is needed.