[HELP] Configurin asterisk for SIP

Hello, I just finish installing asterisk and I am very very lost. My idea is very simple but hard for me to put on practice. I was wondering if anybody has sample how to configure asterisk for sip. I would be using a softphone for know but I relike like to know how to configure user and extensions, etc.

Thank you for your help

I started using the Asterisk@Home relase. Basically does everything for you to set up SIP, plus provides a web-base interface for configuring. If you want a quick start, this would be the place to start