i need help on the thiefs guild mission.

Well...there's a LOT of steps to this mission. A LOT. He should've given 당신 a scroll that lists what 당신 have to do. Look through your inventory and 당신 should find it. If 당신 need help to a certain thing let me know. :)

검색 on 유튜브 i may not know but i know where to go:)

Well once 당신 get Springheel's boots,Cristal ball,
and the 애로우 당신 will have to activate the huge hourglass in the palace basement,then 당신 will get entrance to the old way-under the bloodworks section-of the palace sewers.In the old way 당신 will find an alyed ruin where 당신 have to solve a puzzle 의해 shooting a statue from a special spot that will give 당신 entrance to the palace to steal the elder scroll.

I dont know if I Knew I Would help 당신 Lol