PHP - Fairly Basic Question - Issue With An Include And An Argument That Needs Passing

I think this is a simple question, but I'm just starting out and can't figure out how to do this exactly.

I'm making a demo site for a flower shop. The structure is as such (only listing the particular files in question - once this is done, the rest will be easy)

index.php -> inc_show_colors.php -> showColors.php

The index is to be standard through the site, loading include files into a main content area.  Clicking on a link loads inc_by_color.php (index.php -> index.php?page=by_color )

From there, one of the four colors is selected.

showColors.php contains switch statements for each color. I want to load showColors.php into the main content window when a color is selected, and I need to have it work for all four colors. I'm not sure how to do this, as you can't pass a variable to an include from what I understand.

What's the easiest way to go about this? Keep in mind this is an intro class and "best practices" are not necessary yet, just the simplest solution to get it working.

 I want each of these colors to link to another include file, which will load in its place in index.php.


index.php:
Code: [Select]
<div id="maincontent">
<?php
if (isset($_GET['page'])) {
switch ($_GET['page']) {
case 'by_color':
include('includes/inc_by_color.php');
break;
case 'by_type':
include('includes/inc_by_type.php');
break;
case 'by_occasion':
include('includes/inc_by_occasion.php');
break;
case 'view_cart':
include('includes/inc_view_cart.php');
break;
case 'payment_options':
include('includes/inc_payment_options.php');
break;

case 'home_page':
default:
include('includes/inc_home.php');
break;
}
}
else 
include('includes/inc_home.php');

?>
</div>

inc_by_color.php:
The first link I tried doing in the way I thought would work, but it doesn't. It can't find the include file.
The second one works, kind of - but it just loads the page by itself, not into the maincontent div in index.php.
Code: [Select]
<h1>Flowers Categorized by Color</h1>
<div class="picdivcontainer">
<div class="picdiv"><a href="index.php?page=red"><img src="images/image.png" width="90" height="90" alt="Red Flowers" />
  <p>Red</a></p></div>
<div class="picdiv"><a href="showColors.php?color=white"><img src="images/image.png" width="90" height="90" alt="White Flowers" /></a>
  <p><a href="showColors.php?color=white">White</a></p></div>
</div>

and showColors.php:
Code: [Select]
if (isset($_GET['color'])) {
switch ($_GET['color']) {
case 'red':
$result = mysql_query("SELECT * FROM flowers WHERE color='red'") or die(mysql_error());
while($row = mysql_fetch_array( $result )) {
// Set and trim strings and show the resulting flowers from query
$flowername = $row['name'];
$flowerimage = $row['image'];
$image_path = "images/";
$flowername = str_replace('_', ' ', $flowername);
$flowername = ucwords($flowername);
?> <div class="picdiv"><p><?php echo $flowername."<br />";
$flowerimage = str_replace(' ', '_', $flowerimage);
echo "<img src='images/" . $row['image'] . "' />";
?></p></div> <?php
} 
break;
I realize that showColors.php is probably a really messy way of doing this, but I just need to get it functioning ASAP for now.