the 4th string is the main source of tuning
drop the 6th and 1st string
(it's for D)
the 5th string is the main source of tuning for A
drop the 2nd string
then the after tuning thing
is
uh...
how will I explain...
the fourth string is the MAIN string
first, you uh....
do the thing i wrote in the tabs with the fourth string included
if it has the same pith,
its right
the tune of the 3rd string (open string) should be the same with the 4th string
and
so
on
*if you dont get it, (do you have a piano? organ? keyboard-the electric piano thing;not the one for computer) just use a  piano and press the keys (DADGAD) and tune the guitar- its easier