They figured out the transistor from Sold State Physics.
The way we make transistors today isn't how they used to do it (look up "Alloy" or "Mesa Transistors" sometime).
There are several different types of Transistors. Look up "Bipolar", "Jfet", and "Mosfet" sometime. There are others.
You can design a circuit using transistors, resistors, and capacitors in any Spice simulator. Or rather, you can design the circuit and have Spice simulate how it would perform. Then you can take that circuit and put in on an IC. They have similar components available.
With the tool I posted, or others, you can make the physical circuit on the IC by selecting components from Libraries.
Standard texts, like Gray and Meyer, have sections on the circuits, as well as a chapter on how the circuits are made on IC chips.
But I've always like "The Art of Electronics" for more of a well rounded resource for beginners.
Robert
down
really