RobH_en_tn/hab/02/01.md

I will stand at my guard post and station myself on the watchtower

These two phrases mean basically the same thing. Possible meanings are 1) Habakkuk went to an actual post in the watchtower or 2) this is a metaphor in which Habakkuk speaks of waiting eagerly for Yahweh's response as if he were a watchman waiting at his post for the arrival of a messenger. (See: rc://en/ta/man/translate/figs-parallelism and rc://en/ta/man/translate/figs-metaphor)

to see what he will say to me

"to see what Yahweh will say to me"

how I should turn from my complaint

Here the word "turn" refers to returning an answer. Habakkuk considers what answer he will give concerning the things that he has said. (See: rc://en/ta/man/translate/figs-idiom)