Go to a pet store and get some dewormer or go to walmart they have the same stuff it cost about 4or5 bucks.it will give out directions on how much to give.

 Have your cat examined by a veterinarian who will run a fecal exam to identify all the intestinal parasites infecting your cat.  It is very important to know the specific types of worms the cat has so they can be treated appropriately.  Most dewormers do not treat all types of worms.
 
Worms that look like grains of rice and often move about are usually tapeworms.  These worms are segmented and often shed individual segments in the stool or they can be seen around the cats anus.  These worms are transmitted through the ingestion of an infected flea.  So if your cat has tapeworms it will need to go on a flea preventative as well.
 
There are intestinal parasites that cats get that are transmissible to humans.  So it is very important to identify the type of worm, and get it treated appropriately to prevent human infection.