HseriesWeaksauce

I'm sure this has been posted before but, I know nothing about k series. My car was just stolen and I am replacing an h2b ek coupe with a K20 hatch. My problem is the speedo doesn't work. It's an k20z1 with a 6speeds rsx type s trans (pretty sure an 06 trans). I know there is something that I can do to get it work but not quite sure. I've looked in forums but all the K terminology is confusing me.