If your brake repair problem was with the brake light sockets, you may have had to replace one or more of them. Connecting the wiring to the brake lights may be as simple as unplugging the old socket and plugging a new one in. Or it may involve replacing the wiring along with the new socket. If you have the right tools, you could even disconnect the wires from the old socket and connect them to the new socket directly, but this is intricate work and it's usually not done this way. It's more likely that you would cut the wires leading to the old socket, consult your wiring diagram and splice the new socket onto the old wires.
Some brake work involves the center brake light, usually mounted somewhere on the rear window. Rather than the more typical incandescent bulbs, center brake lights often use LEDs. They may have a simple plug for a new socket, or you may have to rewire each tiny LED socket individually -- it depends on the make and model of your car.
The brake lights might use a common ground, or it's possible that they may use a separate wire to ground each bulb and socket. This isn't usually an issue if you're just dealing with the brake light bulbs. If you properly connect the lights and sockets to the wiring harness, the ground should be taken care of.
As a final step to help maintain your lights (so you can spend less time fixing brakes), you can apply some dielectric grease to the sockets where the bulbs plug in. This nonconductive grease helps seal out moisture and prevent corrosion.
For more information about brakes, brake light wiring and other related topics, stop by the next page.