I still don't understand how if i turn my computer off it will stop carbon producing power stations or whatever.
I'm not actually saying that it would, more that it's not beyond the realms of possibility that it could. As a simplified example, I am Simple Simon after all, lol ...

Let's say before you powered up your PC your areas electricty supply was delivered by exactly 3 carbon producing power stations. When you power on your PC there is more demand for electricity than can be produced by the 3 current power stations. So, to supply enough electricity a fourth power station needs to be utilised. Now then, if you switched off your PC, now that it's on, that fourth power station wouldn't be needed.

Does that make sense?