I've built a cedar planter box measuring 61 inches long x 18 inches
wide x 26.5 inches deep (or high). I want to plant seven (7) IILEX
Crenata "Convexa" (Japanese Holly) in the box but have no idea how to
proceed.

The bottom of the box has holes for drainage. I plan to use either 3/4
inch gravel or lava rocks to facilitate drainage. What I need to know
is: 1) Do I simply place the gravel or rocks on the bottom. I'm told I
should use fabric (landscapers fabric). What role does that play and
does that separate the soil from the gravel or lava rocks?, 2) What
should I plant the "Convexa" in, i.e. should I fill mostly with top
soil and add complete plant food? Should I top it all off with some
much?

As you can see I'm clueless. But my friend asked me to do this for her
and I'd like to do it right.

Thanks so much.