I am fairly new to Autodesk and I don’t have a whole lot time to mess with it for hours on end. I am wondering how to place multiple pieces in the same file. Every time I open a different part it just brings up a separate file. by the way I use the Imperial file that contains all the parts, in case that helps. 
Create an English Standard Assembly (.iam) and then you can click the Place button on the top left corner of the Assemble tab
Thank you!!!