Questions Getting old project data into the Projects Workspace

We currently do not use the Projects module, so there is nothing configured to properly use.  However, we have a spreadsheet with some past and current projects that I was asked to load, just to create a central location instead of a shared spreadsheet.  I have most of the columns mapped except for 3: Project Manager, Quoted Cost and Actual Cost.  It looks like the costs can go into the Cost Budget tab, but I'm really struggling on how to get the PM added.  What has to be configured to get the PM's to show up in the dropdown list?  We use AD for users to login and I played around with adding them as an employee, but I cannot get them to display.