it's not a good idea to create the home directory of a user as a vfat partition. It is better just to mount it under /mnt/fat and allow rw access to this drive to users (or a specific user). If you really really want the home directory a vfat partition you can still do it, you just need to set the permissions correctly.
to create a mount point for vfat with rw access:
#chown /mnt/fat mahal
then in /etc/fstab add:
/dev/hda<x> /mnt/fat vfat users,defaults,umask=000 0 0
where <x> is the correct partition #. This will give all users rw access to the drive, if you want to limit access to just a single user, you need to set the umask permissions appropriately.
You can then mount the drive with 'mount /mnt/fat'. This will also be automaticly mounted at boot. To make home directory for hamal (not recommended)
then change /mnt/fat to /home/hamal.
if you do make the vfat the home dir, I strongly recomend changing the umask permissions to not allow access to the entier "users" group and restrict it the that single user: umask=077
note: umask permissions are the oposite of regular octal permissions, think of it like 777 - <permissions you want set>