►Create a new layer.
►Click the rectangular selection tool.
►Use it to create the rectangle/square.
►Right click the selection
►Select stroke
►Make the color white, and the size 1px.
►Right click on the layer you just made the white stroke on.
►Select blending options.
►Select pattern overlay.
►Choose a suitable pattern with "dots" (If you don't have it, you'll have to download it)
►Adjust the scale until you see the right space between the dashes/dots.
►Select color overlay.
►Choose your color.
►Set the blending mode to Screen.
This question should have been in the GFX section btw. If you need any more help you can VM me.