Hello Brandon
There’s always more than one way to do things in Zbrush, but a common way this might be done is to first sculpt the garment, then use Noisemaker to create a fine detail noise pattern. If the garment will undergo close scrutiny, and you’d like it to be even more realistic, you could use fibermesh to create very fine fabric fibers protruding from it as well.
A note on Fibermesh. Be sure to read the documentation. Many new users don’t understand that the Fiber subtool is a special subtool created by fibermesh that is in a live state, allowing the fibers to be groomed and styled. But this live state can be broken by a number of actions in Zbrush, and you cannot get it back. Its important to get any styling done before changing the subtool from this state.
Meshes can be painted using polypaint.