You need to of posted six (6) post to be able to go into chat.

If you post your Q to Doc John and he does not reply wait untill there is a lull in the conversation and post it again, you can do this without typing it all out again by tapping on the up down arrow on your keyboard, it will then scroll through anything you have written in chat while you have been there. Sometims there are lots of Qs and he will read them all and go through them one by one using your name at the beginning of the reply so that you know its for you.

It is well worth a visit and no you dont have to say anything at all if you dont want to !