To invite a member, go to the members tab from the top navigation bar.
Click Add Members.
Choose the correct role for your user with the dropdown menu provided. To learn user role permissions click here.
Enter an email address or multiple email addresses separated by a comma.
Choose to edit the default subject and message that will be sent. Click Send Invitation(s).
There is also the option to upload email addresses via CSV. You can do this by clicking "Upload Users" next to "CSV Upload":
An Email field within the CSV is required for this upload to work. This is a great way to invite multiple users at once. Back on the users tab, you'll be able to track the status of the invited users.