This the where I show my ignorance when it comes to gears, I understand that the number refers to the amount of teeth on the ring, but I don't know what I have.

I've just looked up my bike on there websites and it says this years model has 50x39x30T, I know mine is a 8 speed, does that refer to 8 cogs at the back?

Gear choice could be an issue here, I normally just stick with whatever feels comfortable at the time...

Again an explanation of gears would be appreciated!!