stick it in barrel jack connector
Do you mean the arduino jack connector ? the one that's near the usb?
or do i need to use an external one?
and i still cant understand how should i connect everything, cause u said: "U1 is the onboard regulator" so - i shouldnt add a regulator? and if i should does it matter which 5V regulator (can i use this 7805 Voltage regulator?) ?
thanx for the patience 