I'll try to simplify
First, try to find 5volt LEDs. That will eliminate the math part. 4-5volts is probably close enough. Then you will need magnet wire. Radio Shack(not sure if they have radio shacks in South Africa) carries a 3 pack of 30, 26 and 22 guage. The 30 works best. You will have to scrape the enamel off the end where you will be soldering the led legs to. The longer leg is the + one and the shorter one is the - one. Tin the ends of the wire where you scraped the enamel off and tin the ends of the LED legs. Solder a length of wire to each one long enough to make it to your receiver. After you have all the leds soldered to there leads, join all the + leads to each other at the receiver end, scrape the enamel off, tin the ends, and the solder them together. repeat with the - wires. You will need a servo extension or a Y connector, depending on if you have a spare plug in you receiver.
If you have an extra channel on you RX or a battery port, just take a servo plug, solder the + led leads to the middle wire, and the - to the black wire, then plug it into your rx, and it will get its power from the BEC. The signal wire will not be used. You can pull it out of the connector casing, or just tape up the end.
If you don't have a spare channel, take a Y connector, and cut off one of the plugs that the servo would plug into. and solder the + led leads to the red wire, and the - to the black wire. Unplug any servo, plug the Y connecter where it was and a plug the servo you just pulled into the uncut servo plug on the Y connector. Tape up the unused signal wire on the light side of the Y connector.
hope that helped.
magnet wire
http://www.radioshack.com/product.asp?c ... d=278-1345
LEDs
http://hosfelt.com/ http://superbrightleds.com/
Edit: forgot to mention to heat shrink all solder joints, or tape them up so nothing shorts out and causes you plane to fall out of the sky.