In the preview area, the preview pane displays the pages of the document that is selected in the document tree. If the document has multiple pages, the preview pane displays the first page initially, but you can view the other pages using any of the following methods:
By clicking
the Previous Page and Next
Page buttons 
on the preview
toolbar (available only for .bmp, .gif, .jpg, .png, and .tif files).
By clicking a thumbnail (available only for .bmp, .gif, .jpg, .png, .tif, and .pdf files).
By scrolling (available only for .doc, .docx, .xls, .xlsx, .ppt, .pptx, .txt, .rtf, and .pdf files).
Notes:
If the preview area is not visible, on the View menu, the Show Preview option is not active (the graphic next to it is not highlighted); and the Show Preview button on the toolbar is not active. To show the preview area, click Show Preview on the menu or the Show Preview button on the toolbar.
If the preview area is visible, on the View menu, the Show Preview option is active (the graphic next to it is highlighted); and the Show Preview button on the toolbar is active. To hide the preview area, click Show Preview on the menu or the Show Preview button on the toolbar.
Document Center can store files of any type that is supported by Windows. However, you can preview only the types of files that Document Center supports the previewing of (such as .pdf, .jpg, .doc, .xls, and .ppt).