Installation Question!

[RadSurfer]

I have the following file:

gfortran-linux.tar.gz, from the official source url,

and I got an /irun folder, my question is:
just how do I install this properly now that it's unpacked please?
Or set it up how to run?  I didn't notice an obvious readme/install,etc.
Looks like its all compiled ready to go apparently.

And is this the "development" package I need to do that C-binding?

thanks
//Rich//