Help me fix my internet explorer!?!?

I had internet explorer 8 and i put up a question last night asking how to steal a friends video off facebook and someone gave me a answer that said " if you download internet explorer 9 then you can download peoples videos to your computer " and so i downloaded internet explorer 9 and now i want to go back ! How do i go back to internet explorer 8?!?!? Thanks in advance !!!!!