This is what I do:
I have a bootable CD with Ghost.
I have a media with the backup file (CD, DVD or USB disk).
Boot the PC from the Ghost boot CD.
Start Ghost (if not setup to start automatically).
Then remove the Ghost CD and insert the CD, DVD or USB disk.
Then select "restore image to disk" (*) (I think that it is called).
Then select the source .GHO file from the backup CD, DVD or USB disk.
Then select the target disk.
Then select "start" (*).
*: I am not absolutely sure about the dialogs in Ghost, but it is fairly simple really.
If the target disk is different in size it will automatically be resized if possible.