How do you plant cactus seeds?

i was at my aunts house and i noticed a cool cactus that she had. i asked for some seeds and she took of a random bunch ( about 10) she told me to put them in a wet napkin for a week and make sure they get sunlights and after a week plant them. im not sure is this is true please tell me the proces. p.s. if u know tell me how the seeds look if their dead or not.