# How can I make my form fields required?

I am new to web design so forgive me if I come off as ignorant. Would some one direct me to a page or give me information on how to make my submit form fields required? Here is my current code:

Code:
<form name="contact" action="process.php" method="post">
<label>Name</label><br />
<input type="text" name="name" /><br />
<label>E-Mail</label><br />
<input type="text" name="email" /><br />
<label>Message</label><br />
<textarea name="message" cols="50" rows="10"></textarea><br />
<input type="submit" name="submit" value="Submit" />
</form>

Any help would be valuable. Thanks!