Well, there are a couple of ways to go about it...
1) Pay someone to write the script for you.
2) Go to php.net and mysql.com, download the repsective manuals, and write it yourself (or mod a script yourself) and if and when you encounter problems, post your questions here...
Here's a basic rundown of what you need to be looking at:
MySQL Manual: UPDATE, INSERT, DELETE, and SELECT queries. Database connectivity.
PHP Manual: working with variables and predefined global variables. Functions such as mysql_query and mysql_fetch array.
Depending on how soon you need this, if you are diligent, it should only take a couple of days to get something up and running. You could learn enough basics in a weekend. Then you can tweak to add things like secure authentication and whatnot.
The main thing is to not feel like you have to have this page up and running tomorrow. Don't rush yourself. Take the time to learn the scripting, and have fun with it.