L.E.D.s

[Kabong]

Agreed Steve.
You can defiantly get a better selection in other voltage's.
I used 12V as my example since 12V Adapters are easy to come by and
Tarolisol wanted a "Newbs how to". This being the same reason i didn't go into resistors.

As for the second LED in the first drawing lighting or not. It would depend on the LED. Some LED's will only fire at there specific voltage and in that case your right it wouldn't light.
Of course this is why I said not to wire them in series but in parallel instead.