You need a stopper with an appropriately sized hole in it for a filter flask. So probably an 8, then you hook up a vacuum source to the vacuum attatchment, in your case it's likely going to be a hand pump. You put your filter paper in, wet with w/e you're running through it, water, organic, whichever. Then you allow the pump to run and pour whatever you're filtering through the funnel.
These filters are meant to work with a vacuum. No vac, no bueno.