Newb post you have probably seen before.Follow

Ask a guard for directions to the [crafting trainer].

-OR- Outside of each crafting instance (in the ethnic villages) you will find an NPC standing right next to the door. This is usually the guy you need to speak to for common recipe books from lvl 3-50.

For books from lvl 50-60, you'll need to travel to Maj'Dul and purchase them from the court where you have good faction or from the big marketplace near the court of coin. (they sell everything there for a slightly higher price.

For books from lvl 60-70, you'll need to take the spires from T-Steppes or Nek Forest up to the Realm of Dawn where you can speak with Penny Dreadful or take the EL spires up to the Realm of Night where you can speak to an NPC near the Dreadnever Crash Site, (IRRC).

Rare recipe books can be obtained as mob drops or purchased off the broker.