From source to game · Docs

Guides are plain text, compiled to Lua. The compiler fills in names, titles and coordinates from the reference data, so a line can be as short as accept 788. From the Orc and Troll starting guide, guides/forever/horde/orc-troll/01-durotar.guide (opens in a new tab):

.guide

guide forever/horde/orc-troll/01-durotar
title Durotar
faction Horde
race Orc,Troll
levels 1-12
zone Durotar
next forever/horde/orc-troll/02-the-barrens

step Gornek
  tip Gornek waits inside the Den, the building just west of Kaltunk.
  turnin 4641
  accept 788
  accept 97279

step Training weapons and boars
  tip The weapons lie around the Den and the training grounds; the Mottled Boars roam the whole valley floor.
  collect 277653 quest 97279.1
  kill 3098 quest 788.1

In this exampleYour Place in the World4641Cutting Teeth788Wayward Weapons97279Abandoned Training Weapon277653Mottled Boar3098

The second step compiles to (goals wrapped here; the compiler writes each on one line):

lua

{
  title = "Training weapons and boars",
  note = "The weapons lie around the Den and the training grounds; the Mottled Boars roam the whole valley floor.",
  goals = {
    { t = "collect", quest = 97279, title = "Wayward Weapons",
      item = 277653, itemName = "Abandoned Training Weapon", count = 6, oi = 1,
      map = 1411, x = 44, y = 67.2, f = "e",
      spots = { { x = 44.4, y = 66.6, r = 45, n = 4 }, --[[ eleven more spawn clusters ]] } },
    { t = "kill", quest = 788, title = "Cutting Teeth",
      target = "Mottled Boar", npc = 3098, count = 10, oi = 1,
      map = 1411, x = 44.49, y = 65.1, f = "e",
      spots = { { x = 45, y = 65.7, r = 56, n = 8 }, --[[ ten more spawn clusters ]] } },
  },
},

Every verb, modifier and condition is in docs/GUIDE_FORMAT.md; guides of your own ship as a community addon.