If you are using a PC and have Microsoft Windows 7 or later, you probably have a free picture editing program from Microsoft called "Paint". If so, you can use it to resize pictures from a camera or scanner. I believe you can also set your scanner up to scan directly into Paint, just as Photoshop users do.

If you already have the picture on your disk, you can open and resize it with Paint as well.

There are lots of free picture editing programs available to download to you PC as well. You can look for them with Google if you don't have MS Paint.