In the system, there is one Admin but you can invite other people depending on your license. The more licenses you have, the more team members you can add.
In order to add a team member, the process is simple. All you need to do is click on "My Account" on the navigation bar, and select "Company" from the pull-down.
On the right-hand-side, you will see the link "Invite Team Members." Simply enter their e-mail address and click "Submit," to add them to the team. Once your team member has confirmed their e-mail, they will show up on this page under the "Team Members" section.