@murtaza131,
1.How to use totally custom page(Thankyou Page)
LifterLMS does not have “thank you” pages as are common in ecommerce platforms. Instead, we show an enrollment notice (which is customizable via your notification settings) and move the user directly into their course / membership. We’ve argued internally many times as to whether or not this is the best solution and while some of our users very much want us to build thank you page functionality, we’ve not had a significant enough number of requests that we’ve found it essential to do so.
For now, you’ll have to do this by using custom code to redirect to a WordPress page of your choice upon purchase / enrollment success. Here’s some example code: https://lifterlms.com/docs/lifterlms-filters/#lifterlms_completed_transaction_redirect
2. How to use Facebook Pixel in Thankyou Page of Membership
You can use this example to see how to add a pixel: https://lifterlms.com/docs/can-add-conversion-pixels-successful-purchases/
I know that we should have direct integrations here with facebook but I just haven’t had the time to build it yet. I’m sorry.