Nash Equilibrium

Hi,

I'm currently revising for an exam and I just do not understand Nash Equilibrium. I've read all my textbooks on the subject, Google, friends etc and I just do not understand it. I've attached an image of the question I don't understand; the question being 'find all Nash equilibria and the sub game perfect equilibria of the game'.

* This isn't homework or anything, I just want to be able to understand it. *

Thanks
Alan

[IMG]file:///C:/DOCUME%7E1/Alan/LOCALS%7E1/Temp/moz-screenshot.png[/IMG]

im a bit rusty on this but i think you can get what you need by answering these questions: (i assume player 1 moves first):

If player 1 chooses R1, what should player 2 do?
If player 1 chooses R2, what should player 2 do?

Knowing that player 2 will follow the above strategy, what should player 1 do?

Thanks for your reply, but I still don't understand. Can player 1 only choose the numbers on the left and player 2 the right?

one of the players will choose from the options on the left (R1, R2). The other player will choose from the options on the right (C1, C2). The question should tell you which way round it is.

I always thought the Nash equilibrium was Steve Nash's stance when he takes free shots...