Sorry, but developing for Outlook is a complex subject, which requires you to have at least a firm grasp of what the application does. You may find this link
usefull[
^], though a bit dated.
And the .pst file format is undocumented (it will be documented for outlook 2010), but reading the .pst file is not the way to go for this project. In most environments, the mail will even not be stored in a pst file.