How to make workflow structure (employee approve/reject process) using visio

I am developing web based application and i want to show the workflow about my developing application to management using visio.

i have visio and i am new to use for creating diagrams in visio.

can i have some sample visio diagram for the below steps...?

1. Login multiple user in the application (admin,user,supervisor approval,Final Approval)
2. Admin can able to travel all the screens (Admin Screens).
3. user can able see only their authorized screen (UserRequestForm)
4. After end user has filling the form, it should go to the supervisor for the approval.
5. supervisor may approve or reject (both need to communicate via mail to end user for the status).
6. if supervisor approved, then "Final Approver" may approve or reject. (both need to communicate via mail to supervisor for the status).
7. if "Final Approver" approved, then the workflow has to be completed.

i know the functional flow as above, but, i am little bit doubt about the symbols and diagrams. what symbols and when we want to use.

kindly guide us to prepare the complete diagram for the demo for management.