[andrewas]

Roll a d20, add in any penalties due to things like Greater malison, compare to the saving throw. If your save is lower than the roll, you pass. If not, you fail. A roll of 1 always succedes, a roll of 20 always fails regardless of the numbers. I think anyway, most gaming systems use that system so its impossible to be 100% sure of the outcome.

The text you see is the current value for your save, followed by the bonus your getting from your equipement. So if its 4 (-2) your natural save would be 6.