dynamo powered lighting for bike and trailer
It might help if you gave more details about your dynamo, and/or what your problem is.

There are basically three different dynamo wiring systems.


Single wire, uses the frame as a return ("earth"), relying on the bearings in your headset being conductive between frame and forks, and clamps or mounting bolts being electrically connected to the frame.
Twin wire, but one of them is electrically connected to the frame.
Twin wire, isolated.


Similarly lights designed for use with a dynamo. So the main thing is just to be sure that if the lights and dynamo have frame connections, they are consistent. If there is a pair of wires, typically one of them has a stripe on and is the earth wire.

For a trailer, the main thing is going to be reliable connectors that you can easily connect and disconnect. If it lives up to its advertising (and I don't know if it will), this system might help (and it also has some wiring diagrams that might be useful to you anyway: Dyna-Snap).
Otherwise maybe something like Anderson Powerpole, or TC-2C1PT