How can I compile my code for different archituctures for example when I'm in FC5 x86_64 I compile for FC5 i386 or compile for arm architecture. (but compile in 64bit for 32bit is more important for me).
I can only suggest some terminology for what you want to do: Look up the topic of "cross compile" or "cross compiling".
I've never tried it. The article http://en.wikipedia.org/wiki/Cross_compiler
implies you would need parts of the 32 bit gcc library. I don't know if this article is uptodate.
"Never let the task you are trying to accomplish distract you from the study of computers."