How do you add 2 photos onto the same background in Adobe Photoshop (somewhat like a shared border)?

Question

My aim is to create a collage, but I find no way to add multiple photographs onto the same "work", whether on multiple layers or not.

Answer 1

Open a new empty document (File > New) large enough to contain your pictures (choose the document size in Preset box or type it in Width and Height boxes) and leave it open. Then open one of the pictures, select it pressing CTRL+A, copy it and paste it on the document. Using the move tool (press V), move the picture on one side of the document. Now do the same things with the others pictures. When you have arranged the pictures on the document you can add text (T) and filters as you like.
For better results learn how to work with Layers.
Here is a tutorial about this topic:

http://www.sketchpad.net/psdlayer1.htm