You can register and submit all supporting material via the conference management web page. You can scan your signed copy of the copyright and submit it electronically as well. You can upload each file individually, just pick a reasonable naming convention (e.g., paper-final.doc, paper-final.pdf, presenter-bio.doc, copyright.pdf, avrequestform.doc, etc..).
Note that you need to include a signature at the end of Part I and at the end of Part IV; you only need to sign Part II or Part III if those sections apply to you.
If you are a lead author signing for all of the paper's authors, please write "signing for all co-authors with their permission" or "signing for co-author with his/her permission" after your signature in Part IV of the copyright form.