Paint Shop Pro v7 » Grid
This tutorial explains how to make small squares on the pic.
First, open an empty (new) image. Then paste the background pic as a new layer. Then go to Layers in the tool line, and choose "New Raster Layer" and click OK.
Now you have an empty layer on top of the background pic, which you can't see. Color the layer in the color you want the grid lines to have. Click on Effects in the tool line, and choose Texture Effects, then Tiles.
Leave the settings as you can see in the screen shot underneath.
Now you have a pic that look like this:
Now, go to Layers in the tool line. Choose Layer Properties, and choose a lower opacity than 100. Take a look at my tutorial "Fading" if you are unsure of how. Then choose the tool called "Eraser" and erase the grid from the areas you don't want it to show. And the result is:
