Configuring dmz on my wireless router?

I am currently using the windy31 router .I use it mainly to connect my ps3 online, however, i now need to configure a dmz but im having problems as i canot access my router configuration page as when i put in my ip address 192.168.33.1,firefox tells me "Firefox can't establish a connection to the server." Pls help as im lost on what to do next.