terminals on the arduino

I'm totally new to arduino. I want to hook an alarm into my uno board. The alarm has a negative and positive wire. Where are the negative and positive terminals on the uno board?

The negative lead to the ground, but you need to know what voltage output the alarm gives before you know if you need to do anything before connecting it to the arduino input, assuming that is what you want to do?

Please not this section of the forum is as it states on the header:- For problems with Arduino itself, NOT your project

This is not a problem with the Arduino itself, it is your project