I got some 404 error

Hello All,
I am a student, and I keep on visiting many blog spots and websites to fetch data regarding some books. Recently, I registered in a web site and tried to upload some document into it. By doing that, I will be getting a pdf document. But, I got some 404 error.
Please help me in fixing this issue so that I can upload my documents.
Thanks for all solutions.

404 Not found.
File not found.
