To be honest, Andy, the best way to learn it is to just play around with it. Especially the filter shapes and the nodes on the screen. After a while, it starts to make sense.
Save your project as a new version, and try different settings.
You are going to horribly mangle a few attempts. Don't sweat it. You still have the original to start from. Another EQ you may find of interest is NyquistEQ, available here:
http://www.dontcrack.com/freeware/downloads.php/id/3176/software/NyquistEq/ This has been a longtime personal favorite.
It is a VST, and you would insert it in the FX bin of a bus or track.
It is extremely flexible, and imho, somewhat more intuitive than the Sonitus EQ.
There are also graphic EQ's, available at sites like KVR-Audio that you may like.
Each EQ has certain characteristics that may or may not be a good fit for a given project, so it doesn't hurt to have a few in your arsenal.
hth