Once a photo is uploaded, it's easy to size it down or crop it with our image editing tools.
There are times you need to resize a photo prior to uploading, for example when you are working with ads requiring exact photo sizes.
Luckily, all operating systems come with an image editing utility. On Windows, you can use Microsoft Paint to accomplish this task.
Here's a link to a Microsoft tutorial explaining how to use Paint to resize an image: http://windows.microsoft.com/en-us/windows7/resize-a-picture-using-paint
Make sure to save the photo to JPEG, JPG or PNG as these are the preferred image formats.