Hi John,
If you are joining a net on analog, it works the same as before.
If you are joining a D-Star net on your local repeater, nothing special is required other than programming your local repeater information in. You will hear all other stations on the net. This also applies if your gateway has been linked to another, or, your system is linked to a reflector. The only time you wouldn't hear other stations on the net, is if you were routing traffic to them, and they weren't set up to route their traffic back to you across the gateway.
For actually programming your radio to go to different nodes, you might want to take a look at some of the presentations we reference on this website. Specifically these, which I highly recommend anyone who is new to programming their radio take a look at:
http://www.dstarusers.org/forums/index.php/topic,35.0.htmlAND
http://www.hamcom.org/presentations/HC2008%20-%20Configuring%20your%20D-Star%20Radio.pdf