The game has a built-in tutorial which you should run through a couple times to learn the basics (then do it again after a week of play).  I don't think it has much of a manual.  As far as I know, there isn't really a manual to explain what the expansions add; you can figure that out by reading the new tech trees and experimenting or reading forum posts.

You definitely want to read this post:

https://forums.sinsofasolarempire.com/319926

Thanks for that link..  Will start reading it.. I guess that is the Beginner guide that one person mention in another post..