brake pedal problems? anyone got a solution!

I don't know much about cars, but i am able to sort problems out with guidance, and i have recently bought a mk1 golf gti cabriolet. The brake pedal seems to be not springing back onto the button which makes the brakes lights come on, hence leaving my brake lights permanently on!
I was wondering if anybody else had experienced this and if so, how do i sort it out as im sure it is pretty easy- jus don't want to go messing around with my brakes!

Thanks!