You have to install GRUB on the MBR (Master Boot Record). To do this just follow this steps:

(First of all, enter your BIOS setup and in BOOT Sequence window choose to boot with CDROM first.)

1) Boot with your Fedora Core Installation CD 1 (or your Redhat Distro).

2) Type "linux rescue" at the prompt.

3) Answer the questions about keyboard and language.

4) Tell the rescue mode to use your proper partition to mount (the one that you want to get booted into)

5) When you come to the console prompt type: chroot /mnt/sysimage

6) Type grub

7) Set the GRUB's root device to the partition containing the boot directory like this:

grub> root (hd0,0)

Filesystem type is ext2fs, partition type 0x83

I have Windows 98 in hd0,0 ; Windows XP in hd0,1, Fedora Core /boot partition in hd0,2 and Mandrake /boot partition in hd0,6. So in my case the command should be: > root (hd0,2)

If you are not sure which partition actually holds this directory, use the command 'find' like this:

grub> find /boot/grub/stage1

This will search for the file name '/boot/grub/stage1' and show the devices which contain the file.
Once you've set the root device correctly, run the command 'setup'.

Then, run the command setup

grub> setup (hd0)
Checking if "/boot/grub/stage1" exists....... no
Checking if "/grub/stage1" exists....... yes
Checking if "/grub/stage2" exists....... yes
Checking if "/grub/e2fs_stage1_5" exists....... yes
Running "embed /grub/e2fs_stage1_5 (hd0)"....... 15 sectors are embedded
succeded
Running "install /grub/stage1 (hd0) (hd0) 1+15 p (hd0,2)/grub/stage2 /grub/grub.conf....... succeded
Done

This command will install GRUB boot loader on the Master Boot Record (MBR) of the first drive.

9) Type quit

grub> quit

GRUB is now in the MBR.

10) Finally, you'll have to edit your /boot/grub/grub.conf, for example whith nano:

> nano /boot/grub/grub.conf

(/etc/grub.conf or /boot/grub/grub.conf or /boot/grub/menu.lst, they are the same file) This file has the boot partitions of the disk/s.

11) Restart your PC without the Fedora Core CD 1 Installation. (or your Redhat Distro)