Use any image-editing program - Paintshop is a common one. Hit "resize" image, and type in the 60 pixels size. You may want to "crop" it first, if, for example it's an image with a lot of yard, and then a pet in the middle, "select" the good area, then "crop."

Both crop and resize are under different menus in different programs, so just keep looking, and I'm sure you'll find it readily.