I would enthusiastically recommend IBM Q [0] and the command-line variant of Hello Quantum [1] to anyone who wants to investigate quantum circuits.

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.

[0]: https://quantum-computing.ibm.com

[1]: https://www.pythonanywhere.com/gists/a5d885816f7dc042a78df11...