php my help

Hi everyone i am a beginner

No i need a help on some fuinctions


I want to make an informations page where people can inform their friends that our server is up

I want to make a informer.php file where will be 1 text box and 1 button called continue

So users can enter their friends email and click on continue button

after they click the continue button the script to check from the database from se_users table se_emails place to check if users email alredy exists to show an error Member is already informed

if email is not in list an email to be sent to the inserted address

including the text :

www.mydomain.com is up I wanted to inform you that i am member there already.

Join me at : www.mydomain.com

by using sendmail function

Can some one help me on this please?