Learning how to validate

[wxdqz]

Yall~
I have ths code:

<form action="/message_sent.php" onsubmit="return validate(this);">
<table width="85%" border="0" height="267">
<tr>
<td width="16%">
<div align="left"><font color="#FFFFFF"><b>First Name:</b></font></div>
</td>
<td colspan="2">
<input type="text" name="name">
</td>
</tr>
<tr>
<td width="16%">
<div align="left"><font color="#FFFFFF"><b>City:</b></font></div>
</td>
<td colspan="2">
<input type="text" name="city">
</td>
</tr>
<tr>
<td width="16%">
<div align="left"><font color="#FFFFFF"><b>State:</b></font></div>
</td>
<td colspan="2">
<input type="text" name="state">
</td>
</tr>
<tr>
<td width="16%">
<div align="left"><font color="#FFFFFF"><b>Message</b></font></div>
</td>
<td colspan="2">
<textarea name="message" wrap="VIRTUAL" cols="50" rows="10"></textarea>
</td>
</tr>
<tr>
<td colspan="2">
<div align="center">
<input type="submit" value=http://www.webdeveloper.com/forum/archive/index.php/"Test" name="submit">
and was wondering how the best way to validate just those three things. I have a php that send it to me just can not figure out how to validate.

Thanks
The Devil