Simple php script

Hi, I want to run a small competition on my blog where someone enters their name and email address in a two line form. I want that form to send the name and address to a php script that will add the details to a database and also the php script must query the database each time the form is sent and if a person is already in the database they are told they can only enter the competition once. I would like to run a monthly competition and so will allow the people to register for the competiton once every month. I would also like a simple newsletter script that would send to all the addresses in the database. That's it.