Create mail/contact form

I tried to create an email/contact form but i'am stuck. (i'am a php-newbie)
Let me explain (sorry for my bad english, it's not my native language)

I have a form with the required fields and the necessary php-code.
There's also some code to validate if a field is empty or there's an invalid
email address.
But how can i display error messages (e.g. empty field), in this (same)
form. (e.g. at the top of the page)
I searching fore several day's but can't find an example.

I appreciate some help or example if possible,

Stephanie
Received on Mon Oct 17 21:09:58 2005