For this part I have to create a page that takes orders in the appropriate boxes and once the "Calculate" button is hit, both the Add-on totals and the Grand total areas are calculated. I have the HTML file pretty much done, it's the JS and the CSS that I and about 10 other people are left in the dark about.

HTML file
<!DOCTYPE html>
<!-- EX02.html-->

<html lang = "en">

<title> Basic Computer Store </title>

<h2> Welcome to the Basic Computer Store </h2>
<h3> choose your Basic Upgrades for a basic price </h3>

<img class = "Left" src = "download.png" alt = "Picture of computer"/>

<th>   </th>
<th>    </th>
<th> Base Price </th>
<th> $999.99 </th>
<th> Add-on </th>
<th> quantity </th>
<th> Add-on Price </th>
<th> Add-on Total </th>
<td> 1.21 Jiggawatt Powersupply </td>
<td> <input type="text" name="PowerSupply" id="PowerSupply" alt="PowerSupply" value=" " size = "2" /> </td>
<td> $1985 </td>
<td> <input type="text" name="PowerSupplyPrice" size = "2" /> </td>

<td> Brainpower (tm) Memory Upgrade </td>
<td> <input type= text" name="Memory" size="2" /> </td>
<td> $1337 </td>
<td> <input type="text" name="MemoryPrice" size="2" /> </td>

<td> Mouse </td>
<td> <input type = "text" name = "Mouse" size = "2" /> </td>
<td> $1 </td>
<td> <input type = "text" name = "MousePrice" size = "2" /> </td>

<td>   </td>
<td>   </td>
<td> Grand Total </td>
<td> <input type = "text" name = "TotalPrice" value =" " size = "2" /> </td>

<input type="button" value="Calculate" onClick="">
<a href = ""> <input type="button" value="exit" onClick=""> </a>
for the CSS file:
I have to find a way to make a notification pop up if less than 1 of any item is ordered or more than 5 is ordered (0-5 minmax), or if any non-numbers are added.

but I'll probably ask that later.