Where can I implement a php code in joomla?

Question

So I'm doing this website with Joomla and I don't have much experience with Joomla. I just want to get the values of some checkboxes and print them into a text area.
I have the script already, I just need to implement it.

Here the raw Html code of the checkboxes:

<div class="checkboxShop">
    <form action="" method="post">
        <input type="checkbox" value="1" id="checkboxShopInput" name="shop" />
        <label for="checkboxShopInput"></label>
    </form>
</div>

And Here is the raw Html code of the submit button:

<form action="/Flex/index.php/shop" method="post">
<input type="submit" value="Buy">
</form>

All I want is to get all the values of the checkboxes and add them to a textarea in index.php/shop. I wrote this code to get the values but i don't know where to add this:

<?php
if(!empty($_POST['shop'])) {
    foreach($_POST['shop'] as $check) {
            echo $check; //echoes the value set in the HTML form for each checked checkbox.
                         //so, if I were to check 1, 3, and 5 it would echo value 1, value 3, value 5.
                         //in your case, it would echo whatever $row['Report ID'] is equivalent to.

            echo "<input type='text' name='message' value='" . $check . "'>"
    }
}
?>

I've read that i need this but I'm not sure how: <?php include "name_of_script.php";?>

Thanks for the help

Answer 1

There are 3 extensions that allow you to add PHP in Joomla: Jumi, Sourcerer, and DirectPHP. Most people prefer Sourcerer since it's easy, solid, and straightforward to use. Direct PHP is a favorite among beginners because it's the easiest. Jumi is a bit more complex than the other 2 (not sure if that has changed lately).