The correct answer to this open question is the following.
Create an advertisement that could have been used in ancient Egypt and Kush to encourage people to use iron.
Ok, to do this correctly, we have to have in mind that gold and iron were two of the most precious raw materials these ancients civilizations valued.
So a good advertisement to encourage ancient Egyptians to use iron would be this one:
"You say you wanted to be like the gods? Well, start here on earth using the benefits of Iron. No more bronze, that's for mortals. Gods use iron, and you are the direct descendant of the gods. So Iron is for you! Iron would pave your way to heaven! Benefit yourself with its many characteristics. Try it once, love it forever. Iron!"