viewing uploaded files in my asp.net page

Display it means display the link or the file content?

If display content then.....
"different files extensions and display" Depends on your browser compatibility to display that file extension. File upload has a property FileContent, which is a stream. That stream can be channeled to a response stream of the same page or a different page. Channelize to a different page is little tricky, alternatively you can save the file and store the path in the session. If different page then page can be called through a IFrame which initialize a context for the page and at the page_load you can get the session variable, read the file in the stream and send it to the response stream. You need to define the content type on the header too.

If display the link then simply add the virtual path of the saved file to a hyper link