HELP ON BLOODWORMS!!!?

i want to grow some bloodworms for my betta fishes. i ve reade websites like ehow and stuff but i still dont get it. I dont go to a lake, pond, etc. I put tap water in a betta contain i got from petsmart and put in dried leaves from last fall. i also put in some old twigs from last fall. i found them in my yard. thee next day, i put a ballon with a short airline tubing and flowed the water. what else? i tried putting in earthworms just now plz tell me how!