I need to have the Solspace Calendar filtered by categories. Is there any working templates out there for reference?
Use the documentation to determine how you should configure your templates.
Try using this parameter to filter by category:
You'll have to be more specific about what you're trying to do for anyone to give you a good example. As for "working templates", EE and how you retrieve parameters for your tags varies widely so again, if you could be more specific perhaps we could help you better.