Laser tripwire to trigger camera recording.

So the background of what I have in mind for this project is this: I'm moving in to a college dorm and would like to create some sort of security system in the event that someone comes in uninvited. /I plan on setting up a laser tripwire at the doorway that, when triggered, will begin recording on a webcam that I have plugged into my desktop. If someone can help explain to me how I could make it so that when the laser is broken, it triggers a function on a script on my computer, I can do the rest. I've gotten no experience with Arduino and am not really sure what they can do, so if someone could help me with this, I would greatly appreciate it.

If someone can help explain to me how I could make it so that when the laser is broken, it triggers a function on a script on my computer, I can do the rest.

The Arduino can read the laser beam sensor. It can determine when the beam is broken.

When that happens, it can send data to the serial port.

Whether there is anything connected to the serial port on the Arduino, or not, is up to you.

If there is, whether there is anything connected to the other end of the wire, or not, is up to you.

If there is, whether or not there is some application running on the PC that is listening to the serial port is up to you.

If there is, what that application does is entirely up to you.