First open the pic you want to resize in MS paint.

Then go to the pull down menu "image", and click on "stretch/skew"

There wil be two boxes where you can stretch or shrink the picture. The number that you enter will be the percent of current picture size. For instance, 50 in each box will make it 50% of original size, while 150 will make it one and one half times larger.

I usually start with 66 to 75 percent in each box, but the pic I used had to be shrunk down to 25% in order to fit on the screen.

If you have Windows XP you can use "save as" to save it is a JPEG, otherwise it will be a bitmap unless you can convert it to JPEG. Also, be sure to save it with the highest color resolution you have. Sometimes mine will want to save it as a monochrome, ie, black and white.
Now that I have told you all how to do this, please remember it and shrink down your pics when they are huge.
Thanks, Matt