Overview/Summary of added features, etc. wanted

Purchased, downloaded, installed and played with this.
Without taking a course in hacking, etc., where can I get an overview/summary of learning how to use, what it all does, etc., in one place, without jumping message to message, etc.?
Example, I want to connect to my shared drives on the network to stream video to the AppleTV…can I, how, why or why not, as this would be good.
Is keyboard & mouse support working? Messages relate back several months, nothing much other than OS update discussions, etc.
Can I get a more concise overview/summary/documentation, spelled out, A-B-C?

Thanking all

seriously!!! Some kind of user friendly/how-to manual would be much appreciated! thanks