Hi! I'm a newbie at this and want to do this with my class. I'm a bit confused on which wires are which, particularly Step 2 and 3. How does the adaptor have one wire going into the PVC pipe but have two coming out? All the adaptors I saw on Amazon has only one wire. I wish there were more pictures so I know exactly which wires and which and what is being soldered. Thanks in advance if I get any reply!