Hi jagall,
When you said nothing seems to work, what do you actually see when you try to add/edit the product in the Categoris/Products admin page?
Do you see everything but the new field you added, or do you see a blank page, or do you see fields displayed but stops right where you added your own field?
If you see everything but the new field, it could be you're editing the wrong file in the wrong place (override).
If you see only a blank page, it could be a syntax error in your code - like an extra semicolon, or missing bracket, etc.
If it displays correctly and stops where you added your own field, then something is wrong with that piece of code you added. :)
Am I correct in assuming that when done correctly that when i go into add products the fields added should appear for data input.
Yes. :)
Just refer to existing fields in collect_info.php file and search for all instances of the field name and then duplicate the bits except change the names to your own custom field name.
I suggest search for products_quantity and try to duplicate (and renaming the duplicate) all instances of products_quantity in collect_info.php.
This would then show up when you try to add a new product of that type.
You then need to edit preview_info.php to preview the value you added.
After that, edit update_product.php to actually save the value into the database.
Each step can be done and tested one by one, so you don't have to worry about preview_info.php and update_product.php until you get collect_info.php displaying correctly.
And forget about /templates/tpl_product_info_display.php for now. That's on the Catalog side and you can ignore it for now until you have at least got update_product.php working.
