This is the main website of Linksys Linksys by Cisco - WRT54G Support
In the FAQ section you can find anything you like.
I you want to change settings in
the router you have to be wired connected.
2 easy ways to enter router
Go to...Start\Control Panel\Network and Sharing Center,click the House/Home Icon first to be able to see the router icon,right click on the router icon and click View device webpage
,find the firewall\configure,select standard,
Apply and exit.
Another way to get there is by typing the router IP address in your web browser.