Sending email from db results

Hello I am writing a send lost password script, that takes the email that a user enters and compares it to the database to see if there is a match and then emails the username and password to the user. I already wrote the comparison stuff and I need to know how to write the mail command, I tried the manual but I am still confused if the strings are $email (the address in the database) and $username and $password what would the mail command look like if it is to say Subject: Your lost password Body of message: Here is your lost $username and $password Thanks in advance. Al