You can send documents in the Draft or Uploaded status to your counterparty by clicking "Send" > "Counterparty" > "via Propdocs" in the document header

If you do not already have a counterparty for this deal, the confirmation screen will ask for the email of your counterparty, inviting them to Propdocs. 

The counterparty will now have access to view and provide suggestions to this document in Propdocs. If you want to give the counterparty view and download access to the document, use the "Grant Counterparty Access" action (only available for Uploaded PDF documents).