This schematic is based on a standard voltage regulator circuit, there are plenty of examples available on the web.  Google It! or try Wikipedea

U1 is the LM7805 series Linear Voltage Regulator, it's job is to convert the 9 volt battery to a steady  5 volt supply.  Pin 1 is Input (+9v), pin 2 is common and pin 3 is output (+5v). You could use a LM7809 and have a steady 9 volt supply. 



The USB connector has 4 pins with pin 1 being the 5v supply and pin 4 the ground the other two are for data etc and Not connected here.



C1 is a filtering capacitor, which honestly I'm not sure if its needed here or not. It is polarized so Pay Attention to how it is connected!

It's always a good idea to plan it out like this to make sure everything will fit into the Tin.

Lets get this thing together!-->