Some strips arrive with wires pre-soldered for testing at the factory, but these might be at either end of the strip and aren't necessarily useful. Check three times to make sure you’re connecting to the INPUT side! Just because you have a strip with wires attached does not mean they’re on the right end.
Tin the pads by carefully melting a little solder onto the pads:
Connect the ground signal/power pin to GND. We’ll use black:
Great! You're now ready to use the strip. You may want to use heatshrink to provide a secure cover for the wires, or stuff hotglue in the end, which will do the same.