When I get icons appearing such as Aeroboost, 30x, Drafting, the Leaf icon, etc.
How do I use them most effectively. Where do I find out what they mean?
It has not been updated in a long time, but it is still helpful: http://titaniumgeek.com/zwift-user-manual-unofficial-running-updates/
Welcome, Paul! We call them Power Ups. Here is another reference for you: https://support.zwift.com/hc/en-us/articles/203964339-PowerUps-in-Zwift.