Pie,
Behringer manuals are more about 'what's what' and such, and because they're translated from (i suppose) German into different languages, can be downright confounding in English or maybe any other than German. I wouldn't know.
That said, T21's are written in New York American English for Americans to understand first, and for others to follow along.
How to use the EQ? That's a whole discussion and debatable topic in itself.
In general, the settings you use with your HB32 2-humbucker guitar that sound 'good' will give you a much different sound if you were to plug in a standard Tele or Strat single coil pup type guitar with those exact same settings.
In another thread, you asked about how to use the vol/tone controls on your HB32. All I'd offer at this point is for you to try some T30 settings on your GM110, with your guitar's controls 'dimed', full-on at 10, to start. Then experiment with backing any or all of them off down in various degrees in pickup combos and listen to the changes as your guitar interracts with the amp. One thing that may be dramatic is what happens to a 'dirty' sound with the guitar's vol control(s) at 10 when you back it(them) down to around 7. You're reducing the output gain of your pickup signal(s) going to the amp and things should not only get quieter, but a cleaner, less overdriven.
And that's just a start...