Placing a link in a message or reply that you post in the forum is easy. All you need to do is copy the URL from the web page you want to reference then paste it on the page with the message you are going to post. Like this:

http://www.vanisource.org/wiki/TLC_10

or this

http://www.vanisource.org/wiki/BG_12.8/wiki/BG_12.8

The best places to source your quotes from Srila Prabhupada's books are:

http://www.vanisource.org/

and

http://vedabase.net/

At Vanisource you get referencs from books
http://www.vanisource.org/wiki/Books

Lectures
http://www.vanisource.org/wiki/Lectures

Letters
http://www.vanisource.org/wiki/Letters

and Conversations
http://www.vanisource.org/wiki/Conversations