how to dual boot fedora 18 and windows 8?

Have you ever installed any Linux distro or partitioned a drive? If not, I recommend you to ask someone for help. It's really easy to break something in the process.

First, prepare your disk - defragment some partition to get free space at the end and shrink that partition. Create new partition in the free space with GParted (for example using Parted Magic)

Then install Fedora, but don't write GRUB to MBR (you'll install some replacement for it later):

Click "Continue" and avoid automatic partitioning, disable LVM and choose "Standard partition". Instead, on the manual partitioning screen select your new partition and choose it as the / mount point. Remember the drive name. (for me it's sda1, for you it will probably say sda2 or sda3)

Continue installing Fedora. When installation is finished, run terminal from the Activities menu and issue those commands: (replace sda1 with your partition's name)

su -c bash
mount /dev/sda1 /mnt
grub2-install --root-directory=/mnt /dev/sda1 --force
umount /mnt
exit

Now boot to Windows and install NeoGrub using EasyBCD.

Clicking the "Configure" button will open your config file. Add something like this:

title Linux
find --set-root --ignore-floppies /boot/tboot.gz
chainloader +1

Leave an empty line at the end and save the file.

It SHOULD work, but I haven't tested it - my setup is quite different.