Netwolf, I was going to post a long screed about lenses, apertures etc. but a lot of it has already been covered by Dennis et al.
Instead, I had a quick look on the Net for additional information you might find useful. Most sites are publicising commercial photography courses, but here are three I found that have some good online information:
http://www.geofflawrence.com/photogr...l_exposure.htm
Look at the side bar items: Exposure / Shutter / Aperture
http://photo.net/learn/making-photographs/lens
Have a look at the ‘Lens’ and ‘Exposure’ topics. Halfway down the ‘lens’ page is a description of wide-angle- normal - telephoto lenses.
The info must be a bit old - the ‘camera’ section seems to be non-digital, but that doesn't affect the basic photo theory.
http://www.photographytips.com/
Click on ‘Equipment‘ and ‘Lenses’. You can only go so far in any topic before having to pay .. ouch!