+ Amazon didn't build any quantum devices.
+ AWS provides a software stack called Braket. 
+ AWS provides classical simulation or access to quantum computers from D-Wave, IonQ, and Rigetti.
+ Many companies (e.g. IBM, Rigetti) have already provided similar software stack/cloud quantum devices. For a more comprehensive listing, please see .
If you start googling (or searching with your engine of choice) about Quantum Logic Gates, Bell States, et c., you'll pick up the basic concepts pretty quickly. Then you can follow the rabbit hole from there.
Personally I have used Cirq and Qiskit to implement some classic algorithms like Deutsch-Jozsa and Shor's algorithm and I would say the two frameworks are very similar to use for those implementations.
So, it would be interesting to get some insights/opinions from someone who has used multiple frameworks. Is there any clear win/loss of those frameworks?