I tired to add some application using the 1st FC3 disk, but it'll prompt me later for Disk2 when I insert it nothing happened I just get the same message back again, but the CDs are ok I just insstalled FC3 from them.
Have you installed any updates to your system since you installed FC3? This will confuse the "Add/Remove Packages" program, though it's not the cause if this particular problem.
What is it that you're actually trying to install?
Paul.