I just open the picture with ms paint, which every pc has, and choose "image", then "stretch/skew", and type in for example 50%/50%, which I think makes the picture about 4 times smaller. Play with it till you find what works, but dont keep shrinking the original. In fact, make a copy...dont modify the original, and try to shrink it only once to the size you want, cause each time you do you lose a lot of resolution and clarity.