Broken computer to external screen [Closed]

I am have a problem I shattered my computer screen so it broken but the computer its self is fine.unfortunately I don't have money to replace my screen but I have an external screen that I can use I know how to hook it up that's not the problem you when I connected the screen to the computer and started it up it started making an alarm clock sound and I couldn't see or do any thing I restarted it and every time the same thing happens again my computer is a Compaq presario CQ57 help me