Take a look at your patch bay. If you look at the front and the back, you'll notice that there are numbers corresponding to each input, and they line up front to back. Inputs vertical from one another should also be labeled with letters A and B. A's are outputs, B's are inputs. Each input routes its signal automatically to the output above it.
Plug your 1/4-inch cable into the back in input 1A. Connect the cable to an instrument, amplifier or effects unit. You can also use patch bays for microphones, but they require balanced cables. Using a patch cable, connect to 1B on the back into your recording device. You should now produce sound and record. This function of the patch bay is called the "normal mode."
Plug a patch cable into output 1A on the front. You can now use this cable to route to another amplifier to better monitor yourself, you can hook it into another recording device, or you can plug it into a soundboard or effects unit for further control. All the patch bay is doing is splitting the signal from back input 1B into front and back outputs 1A; this is called "half-normal mode."
Connect another patch cable to front input 1A. Although you'd think this wouldn't do anything, in most patch bays it activates what is called "parallel mode." This mode splits the signal from back input 1B over the other 1B input and two 1A outputs.