In the future, please try to make better and more descriptive titles. Thanks.
If you want to go from 2.4.18 to 2.6.0, unfortunately it would probably be less hassle to just download the latest to compile, instead of patching as you would have to patch to 2.4.19, then 2.4.20 and so on up to 2.6.0.
There are many tutorials regarding compiling the kernel. ex.
www.tldp.org has a howto on it.
The basic steps are if downloading the tarball, not sure about RPM, I don't use RPM's and never done a kernel compile/install using them, I'd stick to source:
Download the tarball and unpack it in your /usr/src directory.
Create the symlink to your newly created directory called linux-2.6.0 like this:
cd /usr/src
ln -s linux-2.6.0 linux
Now you can cd into linux and it will take you to /usr/src/linux-2.6.0
I never do this step but you can do a 'make mrproper' but I don't think its really necessary for the latest kernel.
Then you want to configure your kernel, if your in X you can do a 'make xconfig' for the GUI config. I prefer to use 'make menuconfig'.
After configuring the kernel how you see fit, save and it will exit.
Now do this to build the kernel:
make
And then to create the kernel image:
make bzImage
If you opted to have modules, you will want to do:
make modules
make modules_install
You can find your kernel in the /usr/src/linux/arch/i386 directory for you to move or copy to your /boot directory.
Regards.