Electronics Schematics Reading
It is something that you will learn as you go through your schooling and it will continue into your career. It isn't something that can be easily explained in a few sentences.

Selecting circuit configurations and the component values that go into them is usually an interative process. You start with what you know, usually related to the external interfaces that a circuit needs to have, propose a general approach based on what the circuit needs to do and your prior experience, and then fill in the details as you go.

Just selecting the component values for a single-stage transistor amplifier is a fairly involved process &mdash; one that you will certainly go through at some point in your schooling. You will see how the selection of one part puts constraints on the possible values of the other parts. Sometimes this leads to impossible situations, and you need to back up and reevaluate previous selections. You will eventually develop an intuition about "ballpark" values for common configurations, which will minimize the number of retries required.

Just be patient, pay attention, and the pieces of the puzzle will start to fall into place for you.