If you would like to add a description for your link, you can simply add it after the url, separated by a vertical bar "|".
E.g. you can use this feature to submit a link which is password protected to our index. Let's say the pass is "123",
then the link that you should submit would be:
http://uploading.com/files/851e57a7/test.txt|123
your pass will be shown in the description for a file.