Asp .net involving windows workflow foundation 4

Actually the web application should solve a vacation slip request for the employees of a company. 1)The employee should be able to make a vacation request to his manager. 2)His manager may approve the request or send back to the employee the request with new dates for new approval. 3)If the manager approve then the request should be forwarded to the human resource manager which should have the same abilities to send the request back to the employee with changed dates. The workflow should be long term and should be stored. Any suggestions or question please feel free to ask. Do not think the things complicated. its just a university project