How do I let website visitors upload their own flash games?

So, I'm trying to create a website that allows its users to upload their own original games, but I don't know where to start. I am comfortable with HTML and CSS, decent at PHP, and a beginner in jQuery as well as mySQL. What do I do?

 

Well in its simplest form the only thing you need to do is let the user upload a SWF file:
http://www.w3schools.com/php/php_file_upload.asp

And then embed the SWF on your site:
http://animation.about.com/od/flashanimationtutorials/qt/embedswfwebpage.htm

Here is a breakdown of what your php script needs to do:

1. User uploads file: game.swf
2. PHP Script moves the uploaded file to /games/
3. PHP Script saves the location /games/game.swf in the database table "games" and gives it a unique ID
4. User goes to /play.php?id=1
5. PHP Script grabs the row with ID = 1 from table "games"
6. PHP Script embeds game.swf into the HTML.