Usually (and by that, I mean by default) Fraps save its screenshots at C:\Fraps, so try checking if such a file exists, and that's where the pictures are being stored. If not, you can open Fraps, go to the "Screenshots" tab, and change the "Folder to save screenshots in", so it can save them to a more accessible location for you.
Also worth mentioning would be the Screen Capture Hotkey (that's the button you press for Fraps to capture the frame on your screen), which by default is set to F10. Again, you can change this hotkey (by accessing the "screenshots" tab on the Fraps menu) if you wish to choose a key that you're more comfortable remembering, and of course, see that it's not set to "disabled" either!