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Even I am a newbie to electronics but I have completed my fundamental course in Microelectronics and Digital Design.
Your question is "how to use transistor as a switch"
For this you need to know the following:
different regions of action by a transistor--active,cutoff,saturation.
MODES Collector-Base j'n Emitter-Base j'n
active region reverse biased forward biased
cut-off region reverse biased reverse biased
saturation reg. forward biased forward biased
The two extreme modes -saturation and cutoff, are very useful if the transistor is to used as switch.The BJT is usually made to operate alternatively in the cut-off and in saturation regions.
The concept of transistor as a switch is more stressed in the "digital design" rather than in your first course in electronics.So I suggest you thoroughly go through the charactersistcis of transistor in every region and how the transition takes place from each region to other.They are the most basic ones.
For reference :
N.N.Bhargava -- I dont remember the title but a very good book to learn your concepts.
Microelectronic Circuits--Sedra & Smith.
The best book is Millman and Halkias.-the Black Pad(popularly known)