qdbus -- a tutorial

I've used this command (qdbus) to help me to open Yakuake in Foresight when I couldn't get a Key that would open it.
Now I'm finding that qdbus sometimes doesn't work and gives a "command not found" error. Up to now, I haven't been able to figure out what I need to install to get it to open.
In any event, this tutorial (and part2 which is linked) will help me get some more out of this once I find out what it needs to work in the first place (have a feeling it's some kde thing)