Pre-requisites:
Permission as mentioned below, on the project template in which users are to be added:
To manage the project template, 'Admin' permission must be assigned to you, your organization, or a user group in which you are a member.
Below are the steps to add users to a project template:
1. In the 'Projects' area, navigate to the project template where users are to be added.
2. Right-click on the required project template and select 'Roles & Users' then select 'Add Users'.
Alternately, in the thumb view, do a mouse hover on the project template thumbnail and click on the 
icon. A layered page opens. Click on 'Add Users'.
3. Follow the steps as required to add users to a project (steps 2 to 7).
Next Collection: Define Configurable Attributes (in a Project Template)