Leveling up a creature from the Pathfinder Bestiary

Question

I have been running a game for the first time and have generally had an experienced GM on hand to help (never done this before). I have an encounter coming up (it pretty much will be the very next thing that happens) where the PCs will face some Hobgoblins. Along with the hobgoblins are the chief who is a level 5 Hobgoblin Fighter. He is supported by two level 3's and a level 5 Goblin Caster (Wizard).

What is the best way to apply the levels to the creatures? (I am sorry if I sound clueless).

Answer 1

You're looking for the rules for “Adding Class Levels” under Monster Advancement. These rules also appear on pages 296–7 of the Bestiary in “Appendix 2: Monster Advancement”.