Prospec fuel filter

open it up, whichever side has the filter element in it, faces the engine.

The closed end or the open end of the filter?

whats is like, a screen or made of lots of little brass balls? if its brass, is it cup shaped?

No its like a funnel thats closed at the end and has an opening at one end. Its made of like mesh.

the smaller or "closed" end will point towards the engine and the larger part or "opening" you could call it will point toward the tank so it can catch the particles. If it was pointed the other way it would still catch most but some may sneak by beacuse they can sneak by the edges as theyre getting pushed trough.