The Arduino software includes a serial monitor which allows simple textual data to be sent to and from the Arduino board. The RX and TX LEDs on the board will flash when data is being transmitted via the USB-to-serial chip and USB connection to the computer (but not for serial communication on pins 0 and 1).
Thank you. I just added a LED on Pin 3 - but without a resistor. It works fine though it shines very bright.
I've got a 220 Ohm resistor. But it doesn't look like the one you posted in the link (brown-red-black on a light brown resisitor). My resistor is kinda blue with black stripes. But it says it's 220 Ohm. What besides the color are the differences between the two?
Does the orientation of the resistor matter?
It doesn't sound like what you have is 220 Ohms.