I recently bought four of these seven segment displays: http://www.electrokit.com/en/leddisplay-7segment-58mm-red-green-ca.49450
I'm having no luck however to make it to work, and since there is no datasheet for the display I'm stuck.
The only thing I've managed to light up is the decimal point. My setup to light the decimal point can be seen below. Note that there are 10 pins on the display, five at the bottom and five at the top. The pins have been aligned to the right of the breadboards (so the red wire is currently attached to the rightmost pin at the bottom).
The red wire is hooked up to the 5v output on the arduino and the blue to the ground. As can be seen the decimal point has been lit up in green, and if I move the red wire four pins to the left the decimal point turns red instead.