Why do so many people abuse animals and what can i do to help these poor animals?

Have you guys seen on Youtube..the story of the Bosnian girl throwing puppies in the river, or people tying their dog up to a tree and leaving it there to rot!? It seems like people love to hurt animals. Like they get kicks out of torturing innocent creatures :'( after I saw the video of the Bosnian girl throwing baby puppies in a river I started having nightmares. Its so disturbing and the only way i can sleep better at night is if i start to help these poor animals in some way. How can i help?? How does one go about helping abused animals? And is there a place where they have crippled cats and dogs up for adoption?