[plt-scheme] Best way to limit/understand what libraries I'm using in DrScheme?

Hi folks,

Pretty new to Scheme I'm just now learning how MzScheme is structured
with its libraries. I would like to understand what libraries I am
using in each language level. Or alternately, I would like to specify
exactly the libraries I want to use.

Right now I think this means that I would use the language "PLT:
Textual MzScheme" and then import any additional libraries I wanted to
use.

Is this the right way to use DrScheme?

Best wishes,

Grant