I'm trying to change how the page selector works on category pages for this:
To: "Page 1 of 6"
But I cant seem to find the file the code sits in to do this. Any ideas?
Refer this link to understand about how to add pagination (it helps to understand the concept).
If you are looking to customize, take a look the below block and temaplates
Block
<magento-root>/app/code/Magento/Theme/Block/Html/Pager.php
or
<magento-root>/vendor/magento/module_theme/Block/Html/Pager.php
Template:
<magento-root>/app/code/Magento/Theme/view/frontend/templates/html/pager.phtml
or
<magento-root>/vendor/magento/module_theme/view/frontend/templates/html/pager.phtml
you can find the declaration of block in layout here
<magento-root>app/code/Magento/Catalog/view/frontend/layout/catalog_category_view.xml
<block class="Magento\Theme\Block\Html\Pager" name="product_list_toolbar_pager"/>