where to insert code for ACF to build the attachment page?

Hi,

Sorry in advance but I am no code writer.
I started a webpage using wordpress with theme twentyfourteen. I also installed the plugin Advanced Custom Fields by Elliot Condon. The website is now under construction and my playground (test area) is at my testwebsite(see private content). I created some pages with galleries containing paintings. With the ACF I wanted to add extra fields like: title, catalog number, width, height, build year, price, material, etc. etc…
I managed to create the ACF group containing a couple of fields and they nicely show in WP-dashboard under library under the pictures of the paintings.

Working with the wordpress theme twentyfourteen, I am able to display the extra custom fields once I click the painting in a gallery.
Clicking on the paining on which I am testing with, brings me to http://www.ltena.com/?attachment_id=688.
This page nicely shows a picture of the paining with the default fields plus the extra fields because I implemented the following code at line 61 of the image.php

<?php
echo ‘Titel: ‘;
the_field( ‘fieldtitel’ );
?></BR>
<?php
echo ‘Catalogusnummer: ‘;
the_field( ‘fieldcatnr’ );
?></BR>

Now I know it is not the best code you have seen ( I am a noob), but it does the job.
Last week I purchases the enfold theme hoping I can tweak the look and feel of the website and I was pleasantly surprised about all the option that can be tweaked.
But after activating the theme I automatically lose my added code (off course!), But where can I add the code in enfold?
I couldn’t find an image.php that looked similar to the one from twenty fourteen. I did found one at wp-content\themes\enfold\config-templatebuilder\avia-shortcodes but it doesn’t come close to what I found in the image.php in the twenty fourteen theme.

Can you please point me in the right direction?
a very big thank you in advance!!!