Users on the Teams plan (formerly Professional Plus) plans automatically have two additional seats available in their Teams Workspace. To invite a new member of your team, head over to the Teams Settings tab on the Account page.
At the top of the page, click Invite Members. You will see the number of available seats left on your plan there.
A menu will appear that will prompt you to enter their email address and role. The invitation will show as “pending” until they accept it. Once they accept they will be a part of your Team!
You can also Invite Members from your Projects page within your Team Workspace. If any of your base seats are not yet filled, you can invite new members by clicking the button next to your Team Member avatars on the right side of the page.