You will get a mail from DIAC in about 24 hours detailing all information. But here is the snip from my mail on how to upload docs.Hi,
I have submitted my 176 application today. The problem that when I login to the account to retrieve the application status, I can see the checklist but I cannot find a place where I can upload the requested documents
Electronic lodgement of applications provides an effective service for applicants to provide documents to the department. eVisa applicants should attach documents online at: https://www.ecom.immi.gov.au/visas/attachment/start.do?attachType=VISA_APPLICATION&group=travel
Don't forget to check spam. Look for a mail with this subject "AUTOMATIC NOTIFICATION OF APPLICATION FOR MIGRATION TO AUSTRALIA UNDER THE GENERAL SKILLED MIGRATION PROGRAM"