External monitor

Hello,
I am having a problem. My laptop LCD screen broke and I don't have the money to replace it, but what I do have is a extra Monitor. I want to hook my laptop up to this monitor but I can't see what I am doing with the screen broken. I wanted to know if there was any buttons I could press when the computer starts up to make it show up on the external monitor. I have tried pressing Fn + F4 but that didn't work. I have a acer aspire 5574zwxmi