Not sure of your question but have a look at File > Automate > Contact Sheet II ...
I can create the contact sheet. I need help with how to print all 3 photos side by side on a 4x6
Create a canvas 6 x 4inches then place your images. How you size them depends on the aspect ratio of the images and whether they are landscape or portrait. If the subjects suit you could have three images 2 x 4 inches to fill the area, or you may want all the image with a margin around the images. You can save it as a JPG for sending out to photoprinting company or to a friend. But always keep your original layered PSD file in case you need to make further changes.