The prompt is:
Every Yale Young African Scholar benefits from and contributes to both the program and wider YYAS community, what contributions will you make? 100 words max.
I have no idea how to start this essay, can someone please advice/give guidelines to follow?
You could paraphrase the prompt. Write it in your own words, without changing the meaning
Sebastian, look at the sample responses that are posted all over this forum in order to gain some inspiration for your response. Do some research on the organization, its activities, and other sample essays that previous applicants have posted. You can do a Google search for that. Based upon the work of the other students, you can develop a an over 100 word draft of your essay. Is strongly suggest that you write about 300 words in relation to the prompt and then work your way down to 100 as you edit the essay for content and responsiveness to the prompt. It will be a bit difficult to research the content and then come up with your own response if you do not have any activities that can be used as the foundation for the prompt. If that is the case with you then you will have to get creative and try to think of future contributions that you can make. While it would be best if you can prove that you will just continue with an activity you are already doing, sometimes, as the saying goes, necessity is the mother of invention. So invent something to present in the response. Just make sure that you can make it sound believable and that you can actually follow through on it in case you win the scholarship to the seminar.
Perhaps have a look at both the program and the YYAS community to see what is lacking. From there, delineate the ways in which it can possibly be improved, ensuring that the methods mentioned are feasible for you to accomplish. Try to incorporate a community element in the solution if possible. You can also draw on something you are passionate about, granted you can tie it to the prompt at hand.