Contact Form To Work (Create Contact.PHP)

I need my website's contact form to work. Here's what the [login to view URL] file should handle: 1. Sending the email to a specified email address 2. Make sure there is a proper email address in the email form, if not give an error message (Please check your email address) 3. Make sure there is something in the subject line, if not, give an error messsage (Please fill in the subject line) 4. Make sure in the message field that if there is less than 30 characters, to give an error message (Your message is too short, please give us some more details) 5. I there is an error, it should highlight read in the box, the error message should appear over "Please fill the following form to send message." in white letters. This should already be coded?