Are you wishing to secure your wireless network?
Can you click the apple icon and then open system preferences and choose Networks.
from there can you choose yor network connection and click TCP/IP and let me know what it shows for your IP address
Can you open the Networks option then choose your Airport adapter and you should then be able to select TCP/IP or advanced.
Can you open an Internet Browser Window and type the gateway address in the following format http://192.168.1.1 then hit enter to open the routers login page.
When prompted type your admin username and password ( If you have not changed it just leave the username blank and enter admin as the password)
When you get logged into the router can you click the Wireless tab then enter a unique Network Name then save your changes.
Once that is saved can you then click the Wireless Security link under the Wireless tab and then choose the type of security you wish to use such as WEP then choose 64bit and enter a 10 digit number in the Key1 box (if in doubt just use your 10 digit phone number with area code) then save your changes.
Once all that is done can you then wait about 2 minutes and see if you can connect your wireless machines using the password XXXXX just set and see if you can get online.
Let me know how you get on or if you have any issues