Although you have never formally studied computing, you have always been interested in computers. You have just read about a computer course that really interests you, but it is only for people who have completed an elementary course.
Write a letter to the college enrolment officer. In your letter
explain why you are writing
describe your circumstances
ask if a special exception can be made for you so you can enrol in the course
You do NOT need to write any addresses.
Begin your letter as follows:
Dear sir,