Got a used sump, how should I run it?

[Jonathan blackwood]

Or what should I put inside? I have a protein skimmer and heater and collection sock of course inside. But what should I use for ?? This is my first sump by the way.

 

[dbl]

Sock if you so choose (some do, some do not) and protein skimmer in the first section, return pump in the next, just as it sits.