how can i hook a volt gauge up to my o2's

[302crew]

i want to hook a volt gauge up to my o2 sensors so i can tell if im running lean or rich i herd its a very good way to check it so if you know tell me how cuase since i converted to carbed there just hanging there not hooked up and where do i hook everything up and what does the guage readings mean like where do i want it to read and can i use this with carbed