That is easy enough, but first I'd suggest you check to make sure you have all the groups added to the user so your
father can have access to the things he may need.
My groups are:
users lp wheel floppy dialout audio video cdrom plugdev power netdev scanner vboxusers
Having that set properly you may want to shorten the initial boot screen to speed up his boot time.
What you are looking to change is the timeout line in /etc/lilo.conf. Here it is set for 15 seconds.
you will need to edit this file as root and then run lilo for the change to take effect
(I use 8 to 10 seconds for my setting.)
# Append any additional kernel parameters:
timeout = 150
# Normal VGA console
To boot into the graphical environment, change this line in /etc/inittab. (Replace 3 with 4).
# Default runlevel. (Do not set to 0 or 6)
That should do it.