If you are a Project Administrator, navigate to Users in the top menu and select the DistillerSR Permission Matrix. On this page, you will see all users associated with your Project. You can grant each user the specific permissions they require on a project-by-project basis.
If you are not the Administrator, you will need to contact the person that is and have them assign the required permissions.
The following link from the online User Guide will help explain the various permissions available: