I'm a communication engineering student. And I'm thinking of doing my project on BB84 protocol but I don't know where to start. As a beginner, are there any documents or tutorials about quantum networks and how to use simulators like QuISP or Simulaqron?
A very good book about quantum networks (with a communication engineering flavour) is "Quantum Networking" by Rodney Van Meter.
Regarding SimulaQron, look at this simple tutorial for getting started:
I strongly suggest to read the main paper on SimulaQron (https://arxiv.org/abs/1712.08032) where the BB84 example is clearly illustrated.