how to setting up AP in linksys WRT54G

[ochin_is_ok]

Dear all,

First, I want to say sorry if there are something wrong in my English speech, because I'm Indonesian. I am a fresh graduate from vocational high school and new employment in industry.

I want to ask you, how to setting up Access Point in linksys wireless WRT54G. I was set this linksys, but it doesn't work. I have a network three like this:
network structure copy.jpg
and I set this linksys like this:

Basic setup:
-internet connection : DHCP
-MTU : automatic
-Local IP Address : 192.168.1.2
-Subnet Mask : 255.255.255.0
-DHCP server : enable
-static DNS : I get from ISP (203.130.196.155, etc)
another configuration is default.

But it doesn't work. Then I try to set internet connection : Static IP, PPPoE, and PPTP, but it still doesn't work. I'm doing ping to modem and local network but I get the message request time out. This is make I can't connect to internet.

What should I do? Should I set the Advanced routing? If yes, please tell me about all configuration!

Thanks for attention