How to configure FCKeditor for ASPX

I configure config for ASPX, i also configure IIS for scrip and executable.
I configure config.aspx with:
UserFilesPath = "http://localhost/OTT/UserFiles/";
and
UserFilesAbsolutePath = "D:\\OTT2\\OnlineTT\\Source\\UserFiles\\";
But is still not work. FCKEditor load, I want to edit text and save itb But when I want to upload files is just see the upload bar, but nothing happen. Also when I click Browser Server in the Images screen i get the error: Internal Server error(500).
Can help me with an example of how to configure FCKeditor for uploading file.