I purchased a led strip for 30cents on ebay and I soldered a positive/negative wire to it and when I put the wires to the battery the leds turn on. i want them to turn on using the receiver but they wont turn on?? only turn on when directly connected to battery... i have 1 extra slot. any help?

They must be setup for 7.4 volts, the 6v from the BEC might not be enough to power them depending on the resistor used or you got the polarity wrong when you connected them to the receiver.

Do you want them on all the time, or be able to switch them on and off with the radio?

If you want to switch them one possible solution is to use a switch designed to work with RC radios:

PicoSwitch radio controlled relay

like B16A2 said they probably have a resister wired in to allow the LEDs to turn on using 2s lipo voltage. Most LEDs normally only run at 3-3.3v and the resister brings the supply voltage down to the LEDs operating voltage