Your right about the shutter speed, thats how long the shutter is open. Your aperture is the size of the opening in the lens, in other words how much light you let in your camera. A low f number is a large opening meaning more light can come in. A high f number is a small opening so less light comes in. You can blur your background by letting more light in with a low f number. However having a high f number means the shutter speed will have to slow down. But that can work the other way round, The more light you let in the faster the shutter speed can be. ISO is how your camera sensor’s sensitivity to light. Some links for you to read now, -
http://digital-photography-school.com/iso-settings. Read it and read it again.

Its a good read. I can't really explain it better than what it says in the link.
Right, another piece for you to read:
http://digital-photography-school.com/learning-exposure-in-digital-photography.
Bet your getting sick of me arnt you,

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If you want to learn about aperture, heres a little task for you when you go out. Put the camera in A. Set your f number to low as you can, around f3.5 and take a picture, then take the same picture with a high f number, remember to focus on the same thing. Then check the pictures against each other. Look at the background.

If the shutter speed goes red then that means your going to under expose your image, so lower aperture till it comes off red, following me?
If your just learning don't go right into manual, try using A and S first, A-Aperture mode, S - shutter priority. In aperture mode the shutter speed is automatic so you don't have to work it out and you can just change the aperture (your f number). In shutter priority mode then the aperture is automatic so you can change your shutter speed without worrying about your f number. Try different things, everyone is a beginner a one point.
If you have any Christmas money or any money saved up then you MUST buy this book, -
http://www.amazon.co.uk/Understanding-Exposure-Photographs-Digital-Updated/dp/0817463003. Its going to be one of the best buys you can think of for starting out with photography. Read it and read it again. Looking forward to seeing some of your pictures as well!