Can you put a FM2 processor in a spot where an Am2 processor was?
No they are two different sockets and are not compatible. You can't put a AM2 or AM3 processor in a FM2 socket and the othe way around. They have a different pin arraignment so it won't work.
If you want to upgrade to a new CPU you will also need a new motherboard. It has been a while since socket AM2 CPUs have been produced so your system is pretty dated.