I don't have a great deal of experience with RedHat in particular, but the following site should be of value : http://kernelnewbies.org/
By the way : be sure to check previous posts. I know that this one has been covered before.
Also, Be sure to at least try and research it yourself. This Link is from a simple search for "recompile kernel RedHat" at google.com.
Hope this helps, and remember, google is your friend.
\"I believe that you can reach the point where there is no longer any difference between developing the habit of pretending to believe and developing the habit of believing.\"
There are different ways to update your kernel. An easy way is to install a RPM update. Or if your a geek like me you can recompile the kernel.
If you can give us a little more information about what your trying to do, it would help us give you suggestions. Are you planning on making a kernel with the mods already compiled in? Are you just trying to tweak your system?
One important thing to note is to always make a backup of your "working" kernel in case something should go wrong.