With ーてform + いただく, you are (in humble form), receiving a favour from someone. (In this case, teaching/instruction/information being given by someone else).
ーたい form + んですが is a polite way of asking for assistance.
博物館に行きたいんですが… ("I'd like to go to the museum...") is really a way of asking for directions.
So the combination, 教えていただきたいんですが is really just a roundabout way of saying 教えてください
note: お願いいたします is onegaiitashimasu, not onegaishimasu (same meaning, different politeness level).