Cheapest way is to use MS Paint as it came with your operating system. I've never used it (I use Picture Publisher 8) but it should work


To change the size of your picture

On the Image menu, click Attributes.

Under Units, click the unit of measurement you want to use for the width and height.

Type the measurements in Width and Height.
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Notes

You can also resize your picture by dragging the image resize handles, located at the lower-right corner and along the bottom and right sides of your picture. (You might need to maximize the window to see the square resize handles.)
If your current picture is bigger than the new size, the picture is cut from the right side and bottom to fit within the smaller area. If your current picture is smaller than the new size, the extra area is filled with the selected background color.