Nowhere to be found in docs: How to setup a goal

Okay, this is the final step in succesfull using Piwik on my server:
“Being able to track if someone clicked the playbutton on my JWPlayer watching a video-clip.”

Some plugins for the JWPlayer are available to use with Google Analytics (so I mailed the creator asking for a Piwik compliant version to create as we all may benefit from it) and some can do a callback in a format like Google / Javascript function / URL.

So to make this simple (like in my CMS), I’d realy would like to let the plugin do a callback to either a javascript function or just a URL.

How to trace it in your stats? Well, I read a lot about goals, but hence, nowhere to find how to setup a goal and in clear language how to trigger one…

So, who could give me a clear example of how to setup a goal in my freshly installed Piwik 0.4.1 and how to trigger it using either a JS-function or just a plain URL with some vars?

EDIT:
One step further?
Now I tried to do:

http://www.mydomain.nl/index.php?piwik_campaign=video&piwik_kwd=JB-Clip

I made it to be a link to click on as a test, but still no campaign data is logged or shown…

EDIT2:
Okay, now found the Goals plugin.

Goal set: video
where the URL contains: flv-JBClip

So now I used a callback like www.mysite.com/index.php?flv-JBClip
And viola…

Now need to figure out how campaigns work (or is OpenX Adserver needed for it?)