External Module Question

Hey guys can someone explain the External Module to me ? Ive read the ToonBOOm Animate Pro Documents. I want to know can i use an After Effects as my external software instead of exporting back and forth from TB AP and how does this work? I connected the external module to my character and background element ,but do i just open After Effects and will my elements be in my new After Effects Composite or do i need to export my elemnets from TB to what i want to do in After Effects. Sorry if i didnt explain this well.