WiFi Connect to Work Lap Top at Home?

I have a PC Laptop that I use for work, and I have been trying to get it to run at home using WiFi Connection to my Mac. When I select my home network, it ask for my WPA2 Key Code, and I don't know if I have one or if I do where or how to find it? I never experienced this problem until a recent upgarde of my Apple Software. I'm not real Tech minded, so anyone who can explain how to help, I would greatly appreciate it. Thanks.