Powering an ATmega328 chip
The Atmega328 can take 5.5V before you risk damaging it.  This is why most Arduinos will use a USB connection to draw power from.  Since you want to use a 9V battery, you will need some sort of voltage regulation to push it down to acceptable levels for the ATmega328.  

You chould use a linear voltage regulator like this one for example.  These are vary widespread and can be adjustable as to which output voltage they will make.  Many are fixed as well.

First off, you will connect your 9V battery to the input rail of the voltage regulator. Make sure you put the postive terminal to the input pin of the regulator and connect the negative terminal to the GND connection of the voltage regulator.  It is wise to attached a capacitor on the input rail going from the positive terminal to the negative terminal.

After you have the battery hooked up to the voltage regulator, you will have 5V being created on the output of the voltage regulator.  At this point you'll connect the output pin to the VCC pins of the ATmega328.  Make sure you connect the GND pins to the voltage regulator as well.  It is also wise to put another capacitor on the output voltage rail as well, one lead to the 5V rail, and the other lead on the capacitor to the GND rail.







simulate this circuit &ndash; Schematic created using CircuitLab



Sparkfun.com has many Eagle diagrams and board files for the Arduino line.  You can also google "Arduino Uno Schematic" if you want the UNO and so on for the various Arduino boards.  The Sparkfun RedBoard is their own clone of the Arduino Uno designs/Duemilanove design for which they offer schematic and board files for Eagle.  The overall functionality is the same as the Arduino, although on some versions, the parts are SMD, and others, not so.