How to give user level access to private GitLab repository?

Update 2021: This answer is out of date, scroll down for the 2021 info.

UPDATE: Gitlab has changed a bit in 2 years, so here is the updated flow.

1. Click on the project that you want to share.
2. Click on the Settings tab (the gear icon on the left).
3. Click on the Members subtab.
4. Add member, and find the user if it exists on GitLab, or insert
   email to send an invitation.
5. Select access level for the user, the possible levels are:

• Guest, can see wiki pages, view and create issues.
• Reporter, can do what the guest can plus view the code.
• Developer, normal developer access, can develop, but cannot push or merge to procted branches by default.
• Maintainer, can do everything except managing the project.

5. For more info about the user access level refer to gitlab official help.
6. (Optional) Set expiration date of the user access.

Old instructions:

1. Click on the project that you want to share.
2. Click on members.
3. Add member, and find the user if it exists on GitLab, or insert
   email to send an invitation.