Also, don't touch the leads on the resistor while you're measuring it, because your own body resistance might skew the reading [mainly a problem with higher value resistors]. Same with a capacitor or any device being measured [for similar and different reasons].
Testing a capacitor is similar, only you will need a capacitance meter [or a multimeter that has a capacitance range] -- also, that meter will have to have a range that is compatible with the capacitor you want to test. For instance, if the capacitor is, say, 3300uF and the meter can read only as high as 1999uF, it won't work. Same with, say, a 10pF capacitor with a meter that can only read down to 100pF.
BUT, after going back are re-reading your question, it occurs to me that what you might mean is how to determine the values of resistors and capacitors when _designing_ a circuit, and if that's the case, my friend, you will have to study electronics.
And check out: * http://fritzing.org/home/ for an application that allows you to do virtual electronics experiments -- kind of like "cyber legos for electronics" -- really cool.
BUT, I can't vouch for any of these because I learned electronics way back in the '70s, so none of this was available for me [i.e. I haven't tried 'em].
