To turn your composite design (layout) into a final image that you can print or send to the lab, you need to use ProSelect's High-Res Production feature (see section below to find out if you have this).

As a first step, you need to get the layout into the production system. The normal way is by ordering it through the shopping cart as part of a customer order. Alternatively, you can use "Send Book to Production" (under the Production menu) if producing books. 

Both of these methods tell Production the final size of the layout to create.

Open the Production window (Production menu -> Produce high-res images), and click on the Composite tab. Your layout design should be listed there. For more details on using ProSelect's high-res production system, see the the ProSelect reference manual under "Making Composite Image Prints" and/or watch the tutorial movies on the Demo Page on the website.

Is your High-Res Production option activated?

High-resolution production is available if you have a "ProSelect Pro" license. If not, you can upgrade to "ProSelect Pro" through the ProStudio Software.com Store Tab.

To see if this area has been activated in your license, open the About ProSelect window (Windows: under Help menu,  or Mac: ProSelect menu) and see if High-Res Production is "enabled".