Why is my wifi disabled?

Hi,

I am new subscriber and just set up the modem today. The internet light is solid green, but for some reason I cannot connect to wifi. None of my devices can detect the modem at all. I connected to the internet using ethernet port and went to telstra.gateway url. Wifi option in wifi page is enabled, but when I check the status of modem, it says wifi is disabled. How do I enable the wifi? It is already enabled in wifi page, but why does it say wifi disabled in status? Please help. No problem with internet as I can browse the net using ethernet. It's just the wifi I cannot connect.
Thanks