As long as the person is a Project Server or Project Online user then you can simply add the user to the project and publish to allow project/project site visibility.

To add the user to the schedule, please follow the following steps:

1. Click the Project Name from PWA
2. Click the schedule in the left Navigation pane
3. Click Project and select Edit and click Build Team
   
4. Select the Resource and Click Add.
5. Click Save & Close.
6. Click Task and select publish
   
7. Click Close and select the Check-In