Go to the top navigation bar, and check out the Share icon (Figure 1).
Figure 1. Share icon.
Fill the Email input with the email of the future member of the project (Figure 2), and an invitation will be sent to the persone for complete the member registration.
Figure 2. Member registration form.
Initially you can give or not the permission to the new member for edit the project just by marking the "Allow to Edit" checkbox.
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