Is this approach correct using workflow for leave application.

Hello everybody.
 
We are developing a small intranet application for leave management , using Windows Workflow Foundation.
We want to expose workflow as a web service on the website.
We are going to use SqlWokfloePersistenceService in our application.
 
We are totally new on workflow's part.
 
How should we proceed ? how to identify which activities would be required?
 Our current approach is :
1)User login 
 
2)User Clicks on apply leave link .
 
3)User fills the web form and submits it. So on submit button we will start the new workflow and this instance would be persisted in the database.
 
4) Now workflow will send email notification to each superior employee (of user) .
 
    exactly at this point we are stucked.
    what to do next?
&n ...