Tony
You're going to have to admit to yourself that the kit you bought is inadequate to the tune of one resistor. As for the E-Bay "kit", what a nice little earner! Three LEDs, three resistors and a Large Letter stamp for a fiver return - I wish I'd thought of
that one.
The correct way is to use one resistor per colour at the very least, to give the right forward voltage for the LED. This value is R Ohms in the following simple equation:
R = (S-F) x 50, where S is the supply voltage and F is the Forward Voltage for the LED.
For UltraBright types, F is 2.0 for Red and 3.3 for Green. On a 12v supply then, R for Red would be 500 and for Green would be 435. If the calculated value isn't listed then go to the next higher value. If the supplier of LEDs doesn't list the forward voltage then buy them from someone who does e.g. Component Shop.
For multiple LEDs I'd advise connecting them all in parallel with the power supply and using one resistor of the appropriate value for each LED. Multiple LEDs on one resistor can bring power considerations into play (bigger resistors).
BTW Doc, Maplin are currently charging 24p per 0.6W metal film resistor
now that's what I call a
very nice little earner!!
Dave M