5V LED where to plug ?

I have 5v LED i want to plug into the board but not sure where.
As long as it goes ON when power is ON and off when power is off its good.
I tried AUX1 but -+ but it ended up developing problem. Printer LCD screen would start sorta blinking and gets disconnected from computer. Once i unplugged it, it worked fine.

A picture of where to plug it in would be very helpful.

Thanks

 

or use a resistor

 

I am not so smart on resistor part. Do i need to buy 7v resistor to make it 5V on exit for the LED ?
How does it work.
I know it will decrease the voltage but how are they rated ?

 

ΔV=IR

12v input - 3.3v current draw = Current draw of LED (you'd have to look this up) * resistance

or just use an online calculator: http://ledcalc.com/

 

In the photo above there are a couple of spots that you could use as a 5v source just make sure the pin isn't being assigned for something else. Taking a multimeter and reading for voltage to test would be a good idea.

or not mess with the ramps board and just get a dedicated 5v power supply. For example from an old usb phone charger. Cut the usb connector off and tap into the 5v supply..

or get a dedicated step down dc to dc converter
or use resistor method mentioned above.