Hey @kelseyw ,

This will depend on whether the segment is a data-driven segment or a manual segment. 

For a data-driven segment, the person would need to match the conditions of the segment. For example, if the segment requires that a person has a certain attribute, you would need to add that attribute to the profile so they qualify for the segment. 

For a manual segment, you can:

• Add People to a Manual Segment via CSV
• Add People to segment using a workflow action

Hopefully this help to clarify and get you moving along in the right direction. ◡̈