Hi,
nice Christmas present. You may get more responses if this was posted in Technology rather than quizzes, but I can give you some guidance.
An SLR type lens usually has two numbers associated with it. First there is the focal length usually in millimetres the scond is the maximum aperture (f stop).
A standard focal length lens which would give an image size similar to the eye is 50mm, a longer focal length would increase the magnification so 100mm would give a 2x magnification. For wildlife shots you would need at least 400mm or more depending on the size of the animal or bird. A single focal length lens is called a prime lens a variable focal lengh lens is called a zoom lens and this is now what is commonly fitted to a lot of camears.
The second number associated with lenses is the aperture or f-stop and this ranges from around 1.8 (widest) to 32 (smallest). The wider the aperture the more light enters the camera a bit like the iris in the eye. So on a sunny day the aperture will need to be smaller than on a cloudy day for a given shutter speed. Prime lenses have the maximum aperture on them e.g f1.8 zoom lenses will have a range, so a 35-80mm zoom will have an aperture of f1.8 to f5.6. The longer the focal length of a lens the smaller (less light ) the aperture will be.
I would recommend going to your local camera shop and asking to see a range of lenes suitable for the subject you wish to shoot.
There is a lot more info on this subject here. Hope this helps.
http://en.wikipedia.org/wiki/F_stop
http://en.wikipedia.org/wiki/Zoom_lens
http://en.wikipedia.org/wiki/Canon_EOS_400D
10:30 Thu 10th Jan 2008