You could probably do it with what you've got, Sharon. You need to reduce the size by about half, so if you reduce the height and width by half, that should do it, as that will also reduce the file size.
You also have a basic editor in the default Windows picture viewer software. Just right click the image and select Edit.
I use Adobe, but I've heard good reports about something called Infran View (I think!), which is free. It should pop up on Google if you search for Free Image Editor, but I'll find it for you when I get back on my PC later.