If you want to save to that folder you'll have to familiarize yourself with the folder setup in your computer. Most likely the path you'll need is C:/Program Files/Plant Tycoon/Images. You'll have to browse to find the right folder to save it in. Or you can save it to your desktop and open folders until you've come to the one you want and move it into there.

Also, be sure on the bottom of the 'save as' box that you are saving as a JPEG file, not another. Depending on what program you're using it may not offer that as the first option. For example, if you're using Paint, it normally saves as a BMP file.
Hope that helps too.

Marcey