how to find a user on yahoo answers?

There is no directory or search feature. If they have a unique username you can do a general internet search, and that will list some of their posts. If their username is not unique, there is no way to easily locate a specific user.

There is no way to look for members here. Yahoo doesn't have a member directory or email address look-up.

You cannot directly find a user on this site by their name/avatar.  All you can do is hope that you know what kind of questions they like to ask/answer and check in those categories to see if their name/avatar pops up.

There is no way to Search for them you have to Spot them on the Q and A Boards Yahoo does not have a way to Search for Specific people

There is no way to search for a user in Yahoo Answers. You can google it, and sometimes you will be directed to a user's question on Answers. 

you cannot do so...........................

The fact that you ask this question shows you are not  smart enough to do it even if it were possible.