Javascript Popup

[socalnate]

Javascript noobie here.  So I'm working on form validation and I'm simply adding up all the input data and checking to make sure it equals 100.  If it doesn't, then I want a popup and to focus on the div container enclosing the inputs "Sum Must Equal 100 Percent."  How do I get the popup to popup?  Here's what I got so far:

<script type='text/javascript'>
// Make quick references to our fields
var action_percent = document.getElementById('action_percent');
var adventure_percent = document.getElementById('adventure_percent');
var animation_percent = document.getElementById('animation_percent');
var arcade_percent = document.getElementById('arcade_percent');
var fighting_percent = document.getElementById('fighting_percent');
var casino_percent = document.getElementById('casino_percent');
var defense_percent = document.getElementById('defense_percent');
var board_percent = document.getElementById('board_percent');
var sports_percent = document.getElementById('sports_percent');
var puzzle_percent = document.getElementById('puzzle_percent');
var multiplayer_percent = document.getElementById('multiplayer_percent');
var driving_percent = document.getElementById('driving_percent');
var shooter_percent = document.getElementById('shooter_percent');
var classic_percent = document.getElementById('classic_percent');
var gadget_percent = document.getElementById('gadget_percent');
var webcam_percent = document.getElementById('webcam_percent');

// Sum the inputs

var total_percent = action_percent + adventure_percent + animation_percent + arcade_percent + fighting_percent + casino_percent 	+ defense_percent + board_percent + sports_percent + puzzle_percent + multiplayer_percent + driving_percent + shooter_percent + classic_percent + gadget_percent + webcam_percent

if(total_percent != 100){

} 

[micah1701]

if(total_percent != 100){

 

        alert("Your total does not equal 100.  Your total = " + total_percent);

 

}