VB.NET: What do I need for creating a chat application for my forums?

I own an online forum: A host server with MySQL database support, domain name, and, MyBB forum software.

I want to create an application 开发者_如何学JAVAthat will let my users log in, and, well, chat.

But I am clueless. What do I need? I have my own database online and host and everything so... What is a good start?

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In order not to reinvent the wheel I'd suggest you to use one of existing solutions. For example this one (AJAX chat application. Built on top of PHP and MySQL).

Also there seem to be a chat module for MyBB forum. Read more.

-- Pavel