Well, I'm not sure why it's not there but you can create it (as root) by:
> mkdir /usr/src/redhat/SOURCES
You might also check that /usr/src/redhat also has the following 5 directories
> ls /usr/src/redhat
BUILD RPMS SOURCES SPECS SRPMS
Then give it another go.
Keep plugging at it. It is often frustrating at the beginning but as you pick up knowledge/skills it gets much better and more rewarding. There's more than one way to skin a cat - and in *nix that is REALLY true ;-)