Finding current balance after a transaction?

I am setting up a check book with Excel 2010 and can't figure out the formula to calculate a current balance after a transaction. I am trying to create a check book in Excel for the simple nature of it for my wife and also to learn more about Excel formula's and such.

Right now the way I have it set up is five columns:

Description|Incoming|Outgoing|Balance|Date
Paycheck|$1000.00|blank|$1000.00|Date
Charge|blank|$200.00|$800.00|Date

This is the first two rows starting at row2. I want to be able to type in the dollar amount in either Incoming or Outgoing column and have it auto-sum in the balance column as shown. I can get it to do it on each cell individually, but I don't know how to write a global variable for the entire column; I don't want to go down the entire column, copy-pasting the formula over and over changing the row values all the way down for god knows how long the check book will become.

Any pointers would be awesome, thanks!

EDIT* Maybe some kind of formula like below?
Pseudo-code: (One cell above + two cells to the left) and of course have some if-statement discerning if it were in the incoming or outgoing column