To add member to your team you need to head over to your Team Administration page.
On this page at the top of the screen you'll see a user invite box where you can add as many user emails as needed separated with commas.
Once a user has been invited, they'll receive an email with a link to join the team. After they've accepted, they'll be added to your team table on the My Team page.
Users that haven't yet accepted an invite will appear under the invite box as pending users. From this list you can reissue invitations by clicking the 'Resend' button or cancel the invite by clicking the close (x) button.