move parts into a sub assembly - keep relations

Hi all,

I am self taught at SW.

I was wondering how can you move parts from an assembly file into a sub-assembly file and maintain all of their relationships?

If you look at the screen shot you will see I have made a bin with a lid, entry ring and rubber flap.

I would like these to form a new assembly within my current top level assembly and maintain their relations to the other parts in the file.

If some one could please list a step by step method they use that would be great!

SolidworksAssemblies