The method I know of involves taking a concentrated sugar solution, putting it in a test tube, and stirring in the sample (being sure to break it up completely). You fill the tube up to the very top, and place a coverslip over it, and let it sit there.
Parasite eggs/cysts will float to the top of the solution, and adhere to the cover slip. You remove the slip and place it on a slide (with or without a stain), and see what's there.

You can't use plain water, because the eggs won't float to the surface in water.