What piece connects to kitchen sink drain?

Recently replaced our sink with a one piece corian sink. Replaced disposal, replumbed the p-trap using a dishwasher tee. I've already figured out that the drain rough-in is too high, so getting that lowered is on the radar.

However, I used a 6 inch endpiece connected directly to the drain on the non-disposer side using the metal nut supplied with the drain basket, and it leaks. The drain came with a plastic flange, but I can't figure out how it fits on any of the PVC pipe I have. I thought the flange on the endpiece would serve the same purpose, but I appear to have been mistaken.

Am I missing something simple? What kind of piece should I be using?

ECN

The tailpiece gasket goes right on the end of the flanged tailpiece

drain

I used a 6 inch endpiece connected directly to the drain on the non-disposer side using the metal nut supplied with the drain basket, and it leaks. The drain came with a plastic flange, but I can't figure out how it fits on any of the PVC pipe I have. I thought the flange on the endpiece would serve the same purpose, but I appear to have been mistaken.

Unfortunately, I cannot figure out what you are talking about, since you are using your terms and not plumbing terms. The flanged tailpiece fastens to the drain with a rubber or white plastic washer between the flange and the drain. Did you slide a regular slip nut onto the pipe under the flange before connecting it. As far as connecting something to your other PVC pipes we can't tell you without a picture of what you are using.