PHP Help - Create a registration system with new member folder

Hello,
I have a PHP Uploader website, that uploads files/folders.

What I want to do, is that whenever someone wants to upload a file/image, they will need to register first, and when they registers, the system will create a folder, so in that specific folder, will be ALL files/images of that one particular user uploaded.

This way, I will know which user uploaded what.

For example,
Bob comes to my website, and registers at mydomain.com
After he registers, he gets a prompt page to login. After login successfully, he gets redirected to mydomain.com/user/Bob. And everytime he uploads something, it will be mydomain.com/user/Bob/uploads/FILES.jpg
(FILES.jpg can be any file)

Please, I know someone out there knows how to do this. I just need help on creating the: create the folder when user registers....the registration system, well I can google one...but I will need help implementing the create folder onto the registration system...

At the moment this would be far too big a project for someone to tackle, unless they're feeling especially kind and dutiful. You should do what you can, like make the registration system and other parts first and then ask for help with specific problems after you've tried some solutions.