Setup two SSID’s on one network

I have a customer that has two linksys wrt54g routers. They have one SSID that is secure for business only. They also had one that was not secure so customers can access the internet. Someone reset the non secure router and I can’t figure out how to set it back up again. They only have one internet modem. My mind tells me that its setup into two VLANS. but I dont think those routers do vlans. I need help fast. Is this even possible????