Here is my code, i just can't get my 'Total and Clear' buttons to work, can someone help?!

<!DOCTYPE HTML>
<html>

<head>
<body bgcolor="#B45F04">

<title>Welcome to my Dead Frontier Shop!</title>
</head>

<body>

<h1><center>I Have the Best Prices On Dead Frontier In game Items!</Center></h1>



<br>

<center><img src="deadfrontier.jpg" alt="dead frontier"></center>




<br>


<form name="myForm">




Please Choose What In game itmes you need:
<select name="Items">
<option value="10">Vulcan $10</option>
<option value="5">AA-12 $5</option>
<option value="3">Corpse Shooter $3</option>
<option value="2">Titanium Blades $2</option>
</select>

Please Choose the color you want:
<select name="Items">
<option value="1">Red</option>
<option value="2">Black</option>
<option value="3">Blue</option>
<option value="4">Purple</option>
</select>
Please Choose When do you need it by:
<select name="time">
<option value="1">Right Away</option>
<option value="2">Within 24 hours</option>
<option value="3">Within the week</option>
<option value="4">On the Weekened</option>
</select>
Please Choose The Amount You want:
<select name="quantity">
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
</select>

<input type="button" value="Total Price" onclick=' var Totalprice = 0;
Totalprice = document.myForm.Items.value * document.myForm.quantity.value;
document.myForm.total.value = totalprice
'>
<td>
<input type="button" value="Clear" onclick=
'document.forms[0].price.value ="0.00"
'/>
</td>

<br><br>
<center><input type="text" name="total"></center>

</form>
</body>
</html>