I have clicked Follow on a YA contributor's name, because I am interested in his/her questions, but how do I actually follow that person?

You ARE following them. If you click your own avatar/nickname, then click the MORE link on your page, you will see a link there for "My Network". They will be there in your "Following" list.

You can also set up a "customized feed" on the Answers Home page to include questions posted by them, so you can easily access them that way.

Yahzmin♥♥ 4ever, many thanks for that accurate advice! I can now follow people with ease! I simply had no idea of how to go about it! Thanks again!