You use Plumber's Putty on the strainer flange, where flange meets the sink on the inlet. As you tighten up the large nut from under neath, excess of putty will be sqeezed out. Remove the excess when finished.

However, below the sink, strainer has its own black washer. Therefore, no putty here.

Drains use on putty. They come with their own washers and nuts. Plastic P-trap has no washer, only nut. Some metal P-traps have black washer.

No use plummers tape from any hardware store

Sorry john, not even close. The tape is for threads. I know this is your first post but most of these guys are pros or experts so be doubly sure of your answers