Creda Reversair?

Hi I hope someone can just give me a very quick answer regarding a tumble dryer Creda Reversair given to us for a tenner yesterday by a kind gentleman because ours was completely broken and we were desperate. It is a little old, but hey for now perfect with this rain. Anyway, there is a low heat and full heat button at the top. It says low heat above it, and when you press the bottom of the button in it has a green line on the top of the button. Do I press the top of the button in or the buttom for full heat? I am sorry of this seemsa daft question but can't find info anywhere. Thank you.