html php and sql connection an upload

Ok, before I start, phpfreaks is my last resort to get help. it seems the people on the other sites are having trouble understanding and/or helping me with this... anyway, here is what I am trying to do: I have a website with a folder structure that I allow users to browse to select a category where they can upload they’re relevant pdf documents, for instance, the root folder is “data”, then they have to select a grade, like grade 12 or 11 or 10 whatever, then a subject say “geography”, “maths” or whatever, inside the selected subject they have to pick a sub category say: if they selected “geography” then ”erosion” is a subtopic for geography. This works well with the folder structure on the website, but I want to change the system to use a sql database with the relevant tables instead of folders. I have already created the sql database and written a php script to connect to the database, now I need to get the rest done…. Can anyone help me write this code, I will put dedicated pages on my website advertising your help!!! I am truly desperate

here is the php code that a guy at daniweb helped me with, but I am getting a couple of problems with the upload.php file...also attached is my database for anyone willing to help me?

Regards
Gabriel Roos