There are several methods in resizing a photo file.
The one that i always use is this one:
1. Right click the jpeg file that you wish to resize.
2. Open with -> Windows Paint
3. Control W -> a window will open, it will show you the horizontal and vertical size of the file in percentage. It will reflect 100% in both fields since the file has not been resized yet.
4. Type in your desired size in percentage. Make sure that you give the same value to each field i.e. Horizontal = 50% and Vertical = 50%. This will decrease the size of your photo file by 50%
5. To check the new size of the resized jpeg in pixels, inches, and/or centimeters press Control E -> A window will appear showing the size of the resized file in pixels. You can also check the size in inches or centimeters just by ticking in the corresponding unit of measurement.
6. You now have your resized photo file, don't forget to save your work!