Handbooks are not much help, always the same, help on what you don't need, but never on what you do need. I have a Peugeot and it doesn't mention 'Lights' under L in index, I'm still searching I only want to change a bulb.
Phone your local library and find out if they have workshop manuals, I loaned one from our local library for a Vauxhall.
If it IS adjustable it is a 'crawl under the car job' to get the the end of the cable with an adjusting nut and lock nut on it. If it's the self adjusting shoe type then either your shoes are worn or you break cable has stretched and needs replacing.
Or if you're in a breakdown service they may have a help desk that will talk you through what to do.
Bob, October 2005