Could someone please help me with my enquiry form, I am trying to stop submitting my form without filling in the necessary fields.

I want to make the description field a required field.

Javascript code

Code:
function validate_required(field,alerttxt)
{
	if (field.value==null || field.value=="")
	{
		alert(alerttxt);return false;
	}
	else
	{
		return true;
	}
}

function validate_email(field,alerttxt)
{
	var reg = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/;
	if(field.value == null || field.value=="")
	{
		alert(alerttxt);return false;
	}
	else if(reg.test(field.value) == false)
	{
		alert('Please enter a valid Email address');
      	return false;
	}
	else
	{
		return true;
	}
}

function validate_form(thisform)
{
	with (thisform)
	  {
		var selectmenu=document.getElementById("00N20000000wFVD");
		if(validate_required(last_name,"Please enter your last name!")==false)
		{
			last_name.focus();return false;
		}
		if (validate_email(email,"Please enter your email address!")==false)
		{
			email.focus();return false;
		}
		if(validate_required(selectmenu,"Please select your country!")==false)
		{
			selectmenu.focus();return false;
		}
	  }
}


this is the section of code in my form I am trying to add teh required field to

Code:
<p class="pform">
<label for="enquiry">Message</label>
<textarea name="description" id="description" rows="7" cols="22"></textarea>
</p>
Cheers for any help.