As always, there are couples of versions of it. 1) Polite and informal, 지금(or 이제) 뭘 해야할지 모르겠어요. (ji geum mwol hae ya hal ji mo reu gess eo yo) (뭘 = is short for "무엇을(mu eos eur)") 2) Implote and informal, (among close friends) 지금(or 이제- i je) 뭘 해할지 모르겠어. (ji geum mwol hae hal ji mo reu gess eo) 3) Quite casual, (when talking by yourself) 이젠 뭘해야 하나.. (i jen mwol hae ya ha na) ^_________^