"Before you can use your custom buttons and links, you need to add them to an object’s (https://developer.salesforce.com/trailhead/force_com_introduction/customizing_user_interface/ui_nav_buttons_links) page layout. Once you do that, you can see and use the button or link on a record detail page."

The Page Layout URL (https://developer.salesforce.com/trailhead/force_com_introduction/customizing_user_interface/customizing_user_interface/ui_page_layouts.htm#ui_page_layouts_overview) does not appear to be correct - could you please provide me a working link?

Thank you,
Matt