Sub woofer Hook Up

I am new to the Audio World and need some help. I have a sub I bought 2nd handed with no manual. It has 2 RCS hook ups in the back and they read:  R-INPUT

                                                                    L - LFE IN

Which one or do both need a cable hooked up to it for the sub to work right?

If only 1 needs hooked up, which one.

I have a new Preamp coming so Im not sure yet but I think it has 2 connections on it?

Any help would be greatly appreciated!