If you're already looking at the Fine Pix Viewer screen, and using an option within that program to load an image file (such as File > Open, or something similar - I don't have the program myself) then there's a fault with the installation of the program. Uninstall it, then reinstall it.
If you're simply double-clicking an image file and nothing is happening, do this instead:
Right-click on any image file.
Select 'Open with' > 'Choose program'
If Fine PiX Viwer is shown (as I'd expect it to be if it's properly installed), scroll down the list of programs until you see it, and click on it.
Click to place a tick in the box marked 'Always use this program to open these files.
Click 'OK'.
(If Fine Pix Viewer does not appear in the list of programs, select 'Other', navigate to where the Fine Pix Viewer program is located, and double-click on it).
From then on, all image files should open in Fine Pix Viewer when you double-click on them.
If you continue to experience problems with Fine Pix Viewer, install a superior (free) image viewing (and manipulation) program:
http://www.irfanview.com/
Chris