If you have DancingGoat MVC example site, the similar approach is used to display ArticleTeaser image. I highly recommend looking at this example as it has a few more very useful Html helpers.
In a nutshell, direct uploader stores these files as Attachments. Your generated class for Employee page type should contain a field of DocumentAttachment type for it and can be accessed like this:
employee.Fields.Photo. You can add it to your view model:
employeeViewModel.Photo = employee.Fields.Photo;
And later in the view you can use it like this:
<img src="@Url.Kentico().ImageUrl(employeeViewModel.Photo.GetPath(), SizeConstraint.Empty)">