I found the PHLEARN tutorial on YouTube very useful only quickly creating a step and repeat in Photoshop. Here is a summary...
1. Select Option-CMD-T (this is the step part)
2. Drag the new layer over and position where you want it and hit Enter
3. Select Shift-Option-CMD-T (this is the repeat part). Every time you hit T (while continuing to hold down Shift-Option-CMD), the shape/motif will replicate with the exact same spacing.
If you want to create all the repeating motifs on the SAME layer, then on the panels layer, select the original layer and hit CMD (where the little square is) and this will select the layer (there will be a little dotted box around your motif). Then repeat steps 1-3 above. All repeating motifs should be on one layer (which will reduce file size).
I hope you found this tip as useful as I did!