I'm new to the site and thought I'd ask a question. I have a 1939 home in CT. I'm installing a new outdoor lamp over the garage and I can't tell which wire is "white" or "black". I guesses and popped a breaker. I'm wondering if I do the opposite would that mean I have it right or does this mean there may be other trouble?

Appreciate the help. Electrical has never been my strong point.