What I've suggested is to:
1. open a console window, also known as terminal (xterm, gnome-terminal, konsole)
2. cd to the directory with your source file
3. execute some commands to build the source (check the manual of gfortran for how to do so)
4. run your executable
Then you'll know what
gfortran -Jobj/Debug/ -Wall -g -c /home/shahbaz/Downloads/CodeBlocks/TestingF/main.f90 -o obj/Debug/main.o
means.
p.s. I've never used a fortran compiler, so I can't help you more.
gfortran -Jobj/Debug/ -Wall -g -c /home/shahbaz/Downloads/CodeBlocks/TestingF/main.f90 -o obj/Debug/main.o
/usr/local/gfortran/libexec/gcc/i686-pc-linux-gnu/4.7.0/f951: error while loading shared libraries: libmpc.so.2: cannot open shared object file: No such file or directory
It seems that the gfortran executable is failing to find its libs, have you restarted gnome/kde after you've installed the gfortran?
Is you library path setup correctly?
You are using gfortran from gcc 4.7.0? The unreleased one, which is still in development?