He's been vague on this. Pull out some US troops from here and there and try not to fight so much - that's about it. Basically, to not be as stupid as Bush.
Issues to address:
The theft of oil revenue from Iraq, a theft that is enshrined in the constitution of the puppet government in Iraq.
Working with Taliban rather than just trying, vainly, to exterminate them.
Leave Iran alone.
Stop Supporting Israel's assault's on Palestine. Full recognition of the state of Palestine, whoever the Palestinian people choose to elect.
Removal all illegal sanctions against Cuba.