When in a project, you can add your customers on the Bid by clicking on the Customers tab.
You have a few options on this tab. You can add and/or remove a Customer, Representative, or Contractor.
Click add Customer to get this screen.
Once you have selected your customer, you can attach a contractor to the customer by right clicking the customer.
You can also add it by selecting the customer and clicking the Add Contractor button.
After picking the contractor your screen will look like this.
Selecting the contractor will give you more information.