Help with Light Configuration wiring

A long time ago I switched my light wiring to make only the headlights come on in the first position. However, when those are on, the back lights dont light. I cant seem to find the how-to or whatever it was online anymore. Can someone point me in the right direction? Im wondering if I can have the headlights and the tailights on at the same time. PS, it was just a simple wire swap.