Newbie q - building devel packages

[Eleknader <eleknader phnet fi>]

Hi!

I'm trying to build my first rpm packages.

Almost every app I've seen packaged are divided in 
foo.version.rpm and foo-devel.version.rpm packages.

I know that the devel packages include header files, but
how to set files for each package with a certain filter
like those ending with .h?

Thanks, Eleknader