Hi everyone! I'm brand new at DMing. I had my third session last night's with my players who are also all new. I'm running LMOP (with a bit of a home made dungeon at the beginning to help introduce the players and myself to the game a bit more) and we just got to the goblin ambush and after the last goblin was alive I had him run off into forest towards cragmaw. My group saw this and more or less said "great! Time to get back to phandalin now that all this is over!"

I know it's not required they go but I had hoped they would want to go fight in the dungeon I had built for them. I don't want to railroad them, because even though they skipped cragmaw we still had a blast, but are there any good ways to encourage my players to follow paths they may not initially want to go?