Hello! I'm giving a very short tutorial on how to make an ícone square (since I often saw many un-square icons). You don't need Photoshop or GIMP or heavy picture editors. Here I'm using link
1. Click "Editor". Here you'll see a Photoshop-like layout.
2. Click "Open image from computer". Select your ícone or any picture you want to make square.
3. Click on the "Crop" ícone on the topo, início left of the panel. Choose "output size" on the "Constraint" dropdown. Enter 200 x 200 or whatever square size you want.
4. Drag the rato over your picture. Hit Enter.
5. Don't forget to save your square picture!