You can add and manage the Roles for the Customer Portal Users from the Portal User Management -> Roles.
By clicking on Create Role, you can add a role for the portal users. Insert the Role details and select the Relationship Type to select the relationship associated with the Role.
Enable the entities that you want to enable for the portal users. You can enable the product for Order & Quote entities.
The Relationship selection is provided to select the relationship that is created in CRM between the contact/account and the entity.
After configuring the Role details, save the details, and the newly added portal user role will be listed under the Roles.