The gasket that you have on the top of the assembly goes under the sink. In place of that gasket, you place plumber's putty.
this assembly is designed to sandwich the vessel sink and your countertop together so it doesn't move.
1. place putty under the top lip of the assembly and insert into sink hole.
2.next insert first large gasket up against the bottom of sink.
3.place sink over top the countertop so that the first gasket sits firmly on your top and the drain assembly penetrates through the top.
4. Now install the last gasket and nut inside the cabinet and tighten everything together.
Thats what it looks like anyway.