If they're on your PC you can right click on the pic, click open with- paint, top tool bar click image, click stretch-skew, go down to say 50% on both and that should do it.
Make sure you save it as a new pic though as this changes the original.
Another way that often works is to email the pictures to yourself. Depending on what email software you use, it'll automatically resize the pictures for you.
I use a software package called www.Irfanview.com. It's a free download and it's pretty simple.