How to connect two asterisk by using SIP trunk!

Hello, Friends:
I set two asterisk. I want to connect the two asterisk using SIP trunk. sterisk A has two different IPs, which 192.168.0.2 and 211.25.64.24. and Asterisk B has a IP(211.25.64.2). How Do I register each other and make dial plan for them. I have read from voip-info.org, but I am not very sure that. Please give me a hand!
thanks
zhu8080

siliconvp.us/

Hello, friend:
i read the link. but I am still not very sure the extensions in sip.conf. Please give me an example of sip.conf. thanks!
zhu8080