Once you have installed your new library...

Choosing an Instrument
When you open Kontakt, and browse the Concert Brass II library, you will see the following list:

In this example, we choose the trumpet instruments.

Once you have reached this point, you will enjoy playing through the vast features that TVEC 3 has to offer.

When you have finished, if you have made changes, make sure you resave the instrument. Otherwise, the next time you it, the default settings will load.