This should be an easy topic for you. The Wright brothers aren't the first people that most students would pick as key influences on their decision to go into diplomacy or intelligence work. You must have had strong reasons for choosing them, then, or you would have selected a more obviously relevant person or event. So, start by stating your main reasons for choosing them. As for how you organize it, its an admissions essay, so ideally the reasons you give will tie into positive character traits you yourself possess, that might make you seem like a good candidate for a scholarship. If you can make such a connection in your thesis, you can then use the entire essay to elaborate on the comparison. It is difficult to give you precise feedback, though, without some sort of draft. Perhaps you could take a shot at one, then post it here.
Sean, EssayForum.com