How do I detect keypresses while application runs in the background?

I'll be upfront, I'm not a great programmer, I primarily work with web based languages (PHP / Javascript) and this is my first attempt to work with C++. I've learned all the basics (via this site) but now I'm stuck.

What I'm trying to do is have a key that, when pressed, performs an action. This works fine expect the program will be running in the background. I came across the function "registerHotKey" but because my ability to understand easily from documentation isn't very good I'm struggling. Documentation here.

I'd appreciate if someone could give me a basic example of how I would use this, thankyou :)

You're going to have to help us help you: what's wrong with the example you posted?