Note: I am by no means an expert, but I consider my knowledge (and the knowledge of the instructables community at large) sufficient enough to educate those who wish to be educated.
Step 1: Resistors
To find the resistance of the four-band resistor:
look at the resistor, make sure the side that has a silver or gold is to the right (there might not be a band with one of these colors, make sure the side that has no band is to the right).
now you simply read it.
write down the first value
write down the second value
the third number tells you how many 0's to add to the number
the fourth number tells you the tolerance.
In the picture the resistor is red green red gold, so that would be 2500-5%. This means that it is 2500 Ohm's and has a tolerance of 5%.