I have bought this as a second wheel. Plugged it into LFs, the only problem is it doeswnt recognise the brake pedal, and there are only 2 axis available (steering and throttle). Any help please?

If the wheel comes with some sort of configuration panel, you need to set the pedals to separate mode. But as the wheel is really cheap low-end model I don't think it has that option. In that case you need to set the pedals to combined mode in LFS from Options -> Controls -> wheel / js -> throttle / brake axes.