Instructions
Open the "Start" menu, then click "All Programs." Click the "World of Warcraft" folder to open contents of the folder.
Right-click "World of Warcraft," and select "Properties." Click the gray "Open File Location" button under "Comment."
Double-click "Screenshots." Every screenshot taken will appear. Double-click the screenshot to view it with your default picture program. The pictures are JPEGS, so almost every image program will open them. If you want to view it with another program, right-click the screenshot and click "Open with."