Need some help wiring tails

So I got a set of 3rd gen JDM tail lights, and go figure they didn't come with the harness. I got the new bulbs already but I am having a hard time finding the sockets. Looking online all of the sockets I'm finding have 3 wires coming off: black, red, and blue. I know the black is ground, but what would I wire the other two to? Any help would be much appreciated!

Edit: Just realized how stupid that sounded... But regardless, where should I look for the sockets? I have an advance autoparts around, and a few other places. I didn't see them at advance so I turned to the Internet but I'm still not quite sure what I need.