Checking file mime type and limiting uploadable files

[potternet]

I have this script, generated by website x5 evolution 9, which is used to process an html form. I wish to limit the file types that people can upload to my server but I cannot seem to work out how to do it. Can anyone help me please?

 

<?php
$settings['imEmailForm_17_5'] = array(
	"owner_email_from" => "eMail Address",
	"owner_email_to" => "admin@potternet.net",
	"customer_email_from" => "do-not-reply@potternet.net",
	"customer_email_to" => "eMail Address",
	"owner_message" => "",
	"customer_message" => "We thank you for your enquiry and will get back to you within 48 hours to begin the process of verifying the information you have sent to us and begin creating the template for your site. 

Kind Regards,
PotterNet Site Admin Team",
	"owner_subject" => "Advert Request",
	"customer_subject" => "Thank you for yourAdvert Request",
	"owner_csv" => True,
	"customer_csv" => True,
	"confirmation_page" => "../advertising-home.html"
);

if(substr(basename($_SERVER['PHP_SELF']), 0, 11) == "imEmailForm") {
	include "../res/x5engine.php";

	$answers = array(
	);

	$form_data = array(
		array('label' => 'Accept Terms & Conditions?', 'value' => $_POST['imObjectForm_5_1']),
		array('label' => 'Name', 'value' => $_POST['imObjectForm_5_2']),
		array('label' => 'eMail Address', 'value' => $_POST['imObjectForm_5_3']),
		array('label' => 'Website URL', 'value' => $_POST['imObjectForm_5_4']),
		array('label' => 'Company Name', 'value' => $_POST['imObjectForm_5_5']),
		array('label' => 'Do you require text in your advert?', 'value' => $_POST['imObjectForm_5_7']),
		array('label' => 'Do you want us to design your advert for you?', 'value' => $_POST['imObjectForm_5_8'])
	);

	$files_data = array(
		array('label' => 'Company Logo', 'value' => $_FILES['imObjectForm_5_6']),
		array('label' => 'Advert Images', 'value' => $_FILES['imObjectForm_5_9'])
	);

	if(@$_POST['action'] != "check_answer") {
		if(!isset($_POST['imJsCheck']) || $_POST['imJsCheck'] != "jsactive")
			die(imPrintJsError());
		if (isset($_POST['imCpt']) && !isset($_POST['imCptHdn']))
			die(imPrintJsError());
		if(isset($_POST['imSpProt']) && $_POST['imSpProt'] != "")
			die(imPrintJsError());
		$email = new imSendEmail();
		$email->sendFormEmail($settings['imEmailForm_17_5'], $form_data, $files_data);
		@header('Location: ' . $settings['imEmailForm_17_5']['confirmation_page']);
	} else {
		if(@$_POST['id'] == "" || @$_POST['answer'] == "" || strtolower(trim($answers[@$_POST['id']])) != strtolower(trim(@$_POST['answer'])))
			echo "0";
		else
			echo "1";
	}
}

// End of file

 

Fingers crossed, someone can help me. lol