cannot understand how to contact a contributor?

If you mean here on Yahoo Answers, the process takes a few steps, and can only be done if the person you want to contact ALLOWS it. Like I do.

First, you need to activate your OWN ability to receive emails from other YA users. Click your nickname at the top left of the page under Notifications, click "Edit Preferences" and select to allow emails from other users.

Once you have done that, you go back to the user you want to contact. You click their avatar or nickname, and IF there is an "email <username>" link/icon to the right of their avatar on their YA profile page, click that. Type your message to them in the box that pops up and send it.

Emails through YA are private, they do NOT reveal the email address of either the sender or receiver. No copy is kept of SENT YA emails. If the person responds, you will receive an email FROM Yahoo Answers, the subject will be "You have received a message from another user". Open the email, as it contains both your message and a special "Reply" link to use to respond to the message, should you wish to do so.

Yahzmin: I asked this question and want to thank you for your answer and let you know that it wasn't me who gave you a thumbs down. I wondered how it got there since you are the only one who has answered, so I thought you might think it was me who thumbed you down - it wasn't I assure you.

I am just going to try what you have told me because I know the contributor I am trying to contact has told me I can but I just couldn't see how to do it. Thank you again.