Form Data and Existing Table Information - ID - PHP/MYSQL [closed]

Newbie!

Building a website form using PHP and MySQL. I need to check if the email address entered matches an existing table1, then a new record needs to be creat I table2 containing the username and password and also selecting the ID number from table 1 into table2. The is auto increment primary key in table1.

I'm not sure how to approach this.....

Thanks!