If you need to add team members, you can upgrade from the billing page or add users. Each user seat costs $49/month.
You can also add the "Agency-Add-on" plan which gives you additional 2 brand projects, 1 additional user seat and the ability to whitelabel to clients for only $250/month.
After purchasing the either the Agency-Add-on or a User seat, you can proceed with adding your team member to your account.
Here's a Step-by-Step Guide:
Click your Profile Name and then select Users.
Click the Invite Users Button.
Fill Out the Information asked and then click Next.
Select the project you want to assign your team member to, then click Invite User.
The assigned team member will receive an email notifying them of the invitation to join the project and prompting them to click Accept the Invitation.
How Do I Add a Team Member to Projects?
Enter a Project and click Project Settings in the right-hand menu.
Inside the menu, click Users.
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Click the users you want to assign to this project, then click "Save."