I also got the 350D for 10 days only. After spending 2 days going through the menu, I also find it a bit difficult to remember all the features...
Welcome... for all dslr including 350D, there are a few basic modes:
1) Full auto mode - all settings are base on the camera's micro-p intelligence. IMO, should try to avoid this mode... after all one main reason to use dslr is to play with the various setting to get better results.
2) Various auto mode (i.e. landscape, night scene, portraits, macro, etc) - same as full auto mode except you tell the camera what type of picture you want to take or what condition you are in.
3) Shutter priority (Tv) - this mode is used when you want to control
how fast the lens open and close. Fast shutter speed is used when you want to freeze moving objects while slow shutter speed allows you to deliberately blur certain object (e.g. water-fall) while the surrounding stationary object is still sharp (tripod needed).
Note: For this mode, the camera will decide for you how big is the aperture opening in order to get the correct exposure.
4) Aperture priority (Av) - this mode is used when you want to control
how big the lens open (aperture size). Big aperture opening (small F number) will allow only certain area of the picture in focus while the background out of focus. For 350D kit lens, try to use F8 - F10 to get a sharp picture.
Note: For this mode, the camera will decide for you how fast is the shutter speed in order to get the correct exposure.
5) Manual Mode - You have total control over the shutter speed and aperture opening. When using this mode, you have to be extra careful with the exposure (too dark or too bright).
Enjoy shooting....