help help help help!!!!!!

I cN'T EVEN LOG ON! i need help

I try to log onto runescape, and get go to the website. That works. Then I click on enter an existing user, and that works. Then I click on a world and It goes to like a black page and then nothing happens. Every time. Then it says it will work if i install something. But i am not about to install sonething that i don't know what it is. Runescape has never been a problem and i have been playing for years. I am on a new laptop though if that has anything...