Error Placing on same page PHP - php

Question

some of my code in addUser.php it pure html
addUser.php
<form action="process/addNewUser.php" method="POST" id="userForm">
<table width="79%" border="0" cellspacing="6" cellpadding="1"
class="tabcont">
<tr>
<td width="47%" align="right">Title:</td>
<td width="53%">
<select name="title"><option value='0'>- - select - -</option>
</select>
</td>
</tr>
<tr>
<td width="47%" align="right">
First Name:</td>
<td width="53%"><input type="text" id="firstname" name="firstName" class="required" /></td>
</tr>
<tr>
<td align="right">Middle Name:</td>
<td><input type="text" id="middlename" name="middleName" class="name" /></td>
</tr>
<tr>
<td align="right">Password:</td>
<td><input name="password" value="" readonly="readonly"
id="password" class="required" " /></td>
</tr>
<tr>
<td align="right" colspan="2">
<input name="addNewUser" type="submit" class="submit" id="submit" value="Submit" />
</td>
</tr>
</table>
</form>
addNewUser.php
Here i am doing validations and displaying error messages and if it is success sending him to another page.
But i want to show an error message on addUser.php instead of validations page. Please give me a sample code how i can do it.

Answer 1

addNewUser.php
Add the message in the session
$_SESSION["ErrorMsg"]="Name already exists";
And in your addUser.php , you put the following code in the place you need to show the msg :
if($_SESSION["ErrorMsg"])
{
echo $_SESSION["ErrorMsg"];
$_SESSION["ErrorMsg"]="";
}