Engaging 4WD

Hi

I'm a total beginner - I just picked up a 1989 Toyota Hilux Surf to get me up to the ski field in New Zealand. I bought it privately, had it checked out and got a good deal.

But, you're gonna laugh at this. I've forgotten how to change it from 2WD to 4WD - something about reversing the vehicle first etc???

I'd be really grateful if anybody could refresh my memory with a short Idiots Guide.

Thanks.