Extra fields on the edit / create member page

Hi. I'm using the members add on for a client portal site, all working out good so far. I don't need or want the ability for members to sign up themselves, so I've added them manually using members > add member in the admin dashboard.

Is there a way to add more fields in here? and access them on a page like: perch_member_get('first_name') . I need to add in more content for each member such as website, address and a tracking code for an analytics dashboard I've built.

Thanks! David.