...high man and welcome in the house and to the hobby.
anyway, i'm new at this stuff myself but if i'm not mistaken the kits come with a threaded petcock/fuel filter that fits into that threaded hole in the bottom of your new tank, here
is a link to a page that shows this petcock/filter combo, just scroll down a bit.
is a link to a thread that shows another alternative.
hope this helps, bozo