see to download torrents you need software like utorrent or azureus

download utorrent it's small and fast

then go to http://thepiratebay.org/ or http://isohunt.com/ and search Dragon Ball or anything like that you will get lots of result find what you want and download the torrent file and open it with utorrent. then utorrent will ask you where to save the files and blah blah

and for your DBZ episode i think you are talking about the one where vegeta bcomes ss for 1st time then here is what happens after it

after vegeta bcomes SS 19 thinks he too will be weak like goku so he tries to beat vegeta up. vegeta acts like a weakling and after playing for a while catches 19s hand and pulls it out then he cuts 19s head. bulma realises 20 is Gero and before vegeta can kill him he escapes to his lab and activates 17 and 18. for remaining series download it

download and watch entire DBZ but i am warning you it affects your studies. I finished all 257 episodes in three weeks