How to install a basin waste/a pop-up drain in your sink ?

How to install a basin waste? Or how to change a basin waste-plumbing tips? The video shows you how to do it correctly. Pls watch it. 

Firstly: Remove the lower washer and backnut from the main waste body.

Secondly: Put the main body with upper washer into the hole of ceremic basin.

Thirdly: Assemble the lower washer and back nut.