To invite a new user to your Workspace go to the User Management area where you can manage the Users that have access to your Workspace.
You can access User Management from the Profile avatar dropdown menu.

From the User Management area, you can add a new User by clicking the "Add User" button.

Input the user's first and last name and their valid email address.
Note: The email address you enter must be their valid address because they will receive an email invitation that needs to be accepted in order to activate their account.

Once the invitation has been sent you will want to edit their project and feature access. You have two options for setting up the user's access:

The Role & Access column on the User Management table shows each user's role along with a count of the projects and features they can reach. Use it to confirm the invite is set up the way you intended without opening their settings.