I'm new to this and don't really know how to read wiring diagrams, but I have to replace the connector into the back of the passenger headlight (somebody messed with it long before me) and got a new connector that I need to splice/solder/wrap to the old wires, but don't know how to tell which of the three wires is High/Low/Ground. What color is what? And if I buy a multimeter, what do I set it to and how do I read it to tell which wire is which? And I think my car was originally made in Canada, since that seems to make a difference. It's a 94 Honda Civic EX (EJ1) Thanks.

 

It's not hard to read a circuit diagram, so it's time you learned. Start by trying to figure it out yourself. Voltage (+) from the battery at the top of the diagram is connected to the grounds (-) at the bottom of the diagram by wires and components in between.

Here's a simplified version of what the diagram tells you:
(+) --> hood fuse box --> white wire --> light switch on steering column --> dash fuse box --> headlights, high beam warning light in cluster, [rear and parking lights, and dash lights]

Do you see the three wires for the headlights and their wire colors?