I cant install adobe flash player i tried!!!!

Hello,
i have a problem !!!! i get on youtube and it says i need to turn on javascript or get the lastest adobe flash player... so i turn on javascript but i didnt let me watch the videos so then i tried to download adobe flash player and it work but something happen and now it says the same thing and it doesnt let me install adobe flash player .....talking about that i need to install flash player 9 and then it doesnt let me install it .....now i suck at computers and i don't know what to do .......someone please help me ....!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! i dont even know if i have it installed or not cause i dont know how to cheak that ......please give me clear steps on how to do it .....