Assemblies
Fusion was designed to use a single environment for design - parts and assemblies. (Drawing exist in a separate environment.) As such you do not see the traditional, separate part, assembly, drawing, presentation templates of Inventor, Solidworks and the like.
As with Inventor, you can work in a bottom up fashion creating parts and them a final document to bring them together. But Fusion was really designed as a top down, in-context program for assembly design. The link below is from the Fusion help and explains both approaches:
In the upper right hand corner of the screen is the '?' button; click it and go to the first item - Learn Fusion. On that page, part way down, you will find tutorials (including the one above) that go over the options in Fusion assembly. Apologies if you've already been there, done that 
A year or more ago, this conceptual leap was difficult for some folk such as myself, coming from a Solidworks/Inventor background, but Fusion team has plugged away at creating lessons to help clear up the concepts - hope it helps. Good luck.
Fred
Edit: Looks like Kevin got there ahead of me.