One of the fields you can use to classify your database contacts is Contact Category. By default, there are several Contact Categories from which you can choose. If you would like to designate a Contact Category not available from those default categories, however, you have the ability to add new Contact Categories.
To do so, first go to Manage Your Account:
Then, select Manage Database Lists:
The body of the Manage Database Lists page is controlled by which List you have selected in the Manage Lists column on the right:
After you've clicked Categories, your page will display this list. Below is an example Contact Categories list:
Note that some of these are Application Default Contact Categories and cannot be edited or removed. You can, however, add new Contact Categories by clicking the add button in the top right corner. You'll then see the below modal:
Just type in the name for your new Contact Category and click Add Contact Category.
Those Contact Categories that have been manually added to your database have both Edit and Delete options available from their Actions menu, meaning you can edit their name or delete them entirely.
After adding your Contact Category, it will then be available to apply to your contact records. Contact Category is also a searchable field from your Advanced Search page.