Some external resources for theatre include:
It explains everything in simple terms and gives you lots of links to other great resources.It’s a constantly expanding resource with concrete step by step guides/processes for almost every aspect of theatre. Take a look at the topics page to find out more about a specific area e.g. accessible theatre, stage management, puppets, sustainability etc.
This is a great free online magazine - they occasionally write articles about tech but is also interesting just generally for theatre features/reviews/opinion pieces from people in the industry. They also have a neat little podcast (I think it's discontinued now but the archive is still on their website so you can listen to all the old podcasts) if that's your thing.