I feel your pain! The forward / backward terminology makes no sense to me; not to mention that I'm at least a bit dyslexic.
Anyway, "forward" means towards the nut/headstock; "back" or "backwards" means toward the tailblock, a/k/a endblock (on an acoustic guitar) - or where the strap button goes at the far end of the guitar body from the neck.

For Headstock vs. Tailstock, see:
https://www.askdifference.com/tailstock-vs-headstock/But I digress. . . Your printed instructions are correct, though a bit cryptic. However, I compare the
open string to: the 12th fret harmonic; and verify with the 12th fret note, fretted.
1. Tune the guitar to pitch, or to the tuning in which it will mostly be played. This is important, because different string tensions will pull more or less hard on the neck, causing slightly different string lengths. Small differences in string length are significant to intonation.
2. If the 12th fret note is
sharp, you need to
lengthen the string. How far to move the saddle is a trial & error process, but you will develop a feel for it - your guessing will get better. Lengthening the string is the same as moving the saddle "backwards". Of course, this makes the whole string ring flat. So re-tune it back to pitch; then re-test intonation. Rinse & repeat until good. What is good? Within 10 cents is basically the outer limit. Most people can hear a difference of 5 cents (I can't

). With a strobe tuner you can get it down to 1 or 2 cents or better.
3. If the 12th fret note is
flat, you need to
shorten the string. Follow above procedure.
Getting maybe too far into the weeds: There is wiggle room. The open string, 12th fret harmonic and 12th fret, fretted, may never 100% agree with one another. This forces you to compromise. Also, due to some obscure but real law of physics, if you pluck a string hard it will ring sharp for a while, compared to plucking it more gently. So, intonation can be set accordingly for players with a hard pick attack.