During my interview for the post I currently hold, I lied about my information and communications technology abilities. This has now backfired on me as I have been asked to convert my mark books into a more secure spreadsheet form. Unfortunately, this is beyond me. My skills do not extend further than using a word processor.
You certainly aren't the first, so don't panic. It sounds like you are being asked to do no more than enter data into a spreadsheet grid, which isn't hard. I'd try to get on a basic course like the European Computer Driving Licence, which you do online. In the meantime, find someone who can show you how. You might ask a student to demonstrate for you, but in a way that makes it look as if you are testing them. I have learned a lot using this basic trick.