While there may be a fair bit of work involved here, it's important to ensure that clarity and detail are presented as much as possible at this stage as this will be a base document for your development team.
Include as many screens and sections as you can. If you aren't sure what to do on a particular screen, at least include copy to try and indicate your thoughts.
Use one of the attached files or try one of the following apps and start wireframing.
Blue
Print
iMockups for iPad
Balsamiq
Mockups
Lucid
Chart
Just In Mind (Web app)