If you have a collection of similar photos that you want to put together, you can do this pretty easily using the Auto Select Layer and Align features. I used nine photos in my example.
With the Shift key held down, click-and-drag with the Rectangular Marquee tool (M) to create a square selection in your image.
Press Command-N (PC: Control-N) to create a new document, and use the Move tool (V) to drag-and-drop the selected pixels into the new document. Press Command-T (PC: Control-T) for Free Transform, and then scale the size down (with the Shift key held down to constrain the proportions).
Switch back to the Rectangular Marquee tool, and drag-and-drop the selection border (the marching ants) from the first photo onto the second photo. Use the Move tool to drag-and-drop the selected pixels into the new document.
Press Command-Shift-T (PC: Control-Shift-T) to apply the same transformation to the second image.
Repeat Steps Three and Four until you have a square selection of all your photos copied onto the main document. Don't worry if the images are not alignedwe'll do that next.
Use keyboard shortcuts to switch back and forth between the Rectangular Marquee and Move tools: M for Rectangular Marquee and V for Move.
With the Move tool selected, turn on the Auto Select Layer checkbox in the Options Bar. Click-and-drag across the top three photos to select those layers.
Then, in the Options Bar, click on the Align Top Edges icon (the first alignment icon on the left).
If necessary, click on the top-left photo and nudge it to the left, then click on the top-right photo and nudge it to the right. Click-and-drag to select all three of the top photos and then click on the Distribute Horizontal Centers icon (the second alignment icon from the right).
Click-and-drag to select the three photos on the left-hand side, and in the Options Bar, click on the Align Left Edges icon (the fourth alignment icon from the left).
Continue selecting and aligning/distributing layers until you have an even grid of photos. Click-and-drag around all of the photos to select all the layers, and then click-and-drag the grid of photos to the center of the page.
Here I added some text.
In this example, I added a Hue/Saturation adjustment layer at the top of the layer stack and turned on the Colorize checkbox.
Variation 1: Hue/Saturation adjustment layer
In Variation 2, I used four photos and added a thin stroke border around all four images.
Variation 2: Thin stroke border added
This variation uses a wide layout with a black background and four photos, each of which has a thin stroke border.
Variation 3: Wide layout with black background and thin stroke borders