s-trap trouble

I'm trying to connect an s-trap to a new bathroom sink--and I think I got the pieces confused. It seems that one of the curved joint pieces has one threaded end and the other end just has some kind of lip on it. The other curved joint piece has two threaded ends. Which piece connects to the drain assembly of the sink (threaded or unthreaded) and which piece connects to the waste pipe? Also, how do you connect the unthreaded end to the other piece with provided slip joint nut-thing? HELP!

Kathy

If you bought a new S-trap it should have everything you need to connect it. S-traps are illegal in my area so I don't have much info to give regarding that application. I have replaced them though and most times the 2 bends look similar but through a couple tries you'll find that there is one certain way they match up.

"S" trap

We would almost have to see a picture of the trap. The piece with two threads would be the one that attaches to the sink drain, but the other piece should either have a long straight outlet, or if it has a thread to attach to a separate straight piece, it should have a "captive" slip nut to enable it to attach to the other piece. In any case the assembly should be self evident as to how it goes together.