power supply arduino nano

newbie question: i would like to use my arduino nano without my computer, with an external power supply. where would i connect a battery or cable? if i use a cable & plug i would need a adaptor - but for which voltage and which how much ampere?

this is what is going to be connected to the arduino nano:


could i use something like this?


what about the amperes?

My Nano has also a pin that accepts as input voltage 7-12 V and has the regulator on board. Additionally it has a 3.3V output pin which I don't know how much amp it will provide. It's enough however for a display and a wireless USB breakout board in one of my projects. Somewhere I read that the 3.3V are only provided when powered from USB, but in my tests it also works when powered from battery. See http://ulrichard.is-a-geek.net/?p=3 for example. This example project requires about 60mA @ 9V. You may however need voltage dividers on the signal lines from Arduino to the 3.3V display. Some devices accept higher signal voltages, some don't. On the signal lines from display to arduino, you're lucky. The 3.3 are above the treshold for the 5V inputs.