Sure it is possible, but a huge security risk for you, if you don't secure it properly.
Unfortunately, you will need a server side script (PHP, Perl, ASP) that will handle the upload/file write routine.
This is very advanced, and if you don't know anything about programming I would strongly advice to keep away from such advanced stuff until you know more about server security.
Just an example:
Imagine, that you don't check the file that gets uploaded and don't secure the upload at all. Someone could easily upload an script that will be executed on server side.