In the "Settings" tab, click on "General" you will be taken to the Custom Attributes screen. Click "New Custom Attribute," name your attribute and from the dropdown menu select the attribute type. Click "Create".
Radio: This option allow you to set one value per profile (i.e. Favorite color? Red OR Blue).
Checkbox: This option allows you set more than one value to a single profile.
Text: This option allows you to type note for remarks about an individual with a free form text option.
Number: Add a number range to a segment on different ranges.
Tag: This option allows you to set one singular value to your entire data set.
Date: Add a date as an attribute to timestamp your audience.
Date time: Add a time and date as an attribute to timestamp your audience.