Hello,
When I bought my first Arduino kit I got with it a connector for 9 volt rectangle battery.
I never tried to use it and now when I'm trying its not working...
is my Arduino broken?? the battery is not new, but almost new...
Even my multimeter says that!
Any ideas?! 
note: I dont want to buy anything complicated from ebay or something cuz in my country it takes more then a month! if it will be something simple maybe Ill be able to find it in stores...
thanks so much for help! 
Multimeters don't say "It's almost new" they tell you a voltage. What is it? And where on the Arduino have you connected the battery connector?
Steve
slipstick:
where on the Arduino have you connected the battery connector?
I just connected it to the right place on the board...
neer the USB port there is a place for the power plug.
The right place ?
It connects to the plug in connector on the same board side as the USB.
Does the power light light up?
What voltage does the battery show when connected ?
try to open up pinout of the connector . And make sure that the longer plate inside is connected to the negative side of the battery and shorter one to the positive.