To create a custom Data Category you want to go to the Tool, Process or Individual you want to add the Category for.

Then go to the second tab and click on the Data Categories drop-down. Type the name of the data category you want to create. For example: "Custom Data Category".

Once done click Save on the top right. This Data Category will now appear on your Privacy Portal and all the other relevant documents.

If you want to add examples in your Privacy Portal, you can go to Privacy Portal > Privacy Policy and add examples.

Press Save Changes and now they will appear on your policies.