I have a liksys wireless system in my room and downstairs my brother has the modem of broadband which connects to my wireless system and it is wireless G Pci adapter and i want to connect my ps2 online adapter to my computer and i have the thick ps2 and i dont know how to get on donny

You want to connect your ps2 to your computers eithernet port and use the wireless G pci adaptor on your computer to go online with your ps2? You can't which is why it's not worrking. You're going to need Logitech Play Link it's a wireless adaptor for the PS2 that allows you to connect wirelessly to your wireless pc router.

I thought you could bridge network connections?