The system accepts "doc," "tif," "tiff," "pdf," "jpg," "jpeg," "gif," "png," "txt," "rtf," and "bmp" files. Ensure the file is saved on your hard drive with the appropriate extension (i.e. .doc, etc.) and make sure you do not change the file name upon selecting it in the upload form.
You can also save your documents as rich text format (.rtf) files in most word processors. Go to the file menu, select Save As, and choose that format to save your file.