For general advice on how to structure a PS etc I guess the people in the PS sub-forum here
can help you (I was hoping they'd have a sticky I could link to, but it seems not...).
However as the people above have said: the PS is you telling the university why you want to come and study Land Economy for three(+) years and how you're qualified to do so. If you don't know that
yourself, then you need to do some proper research into it, and seriously think about whether it's what you even want to apply for. If you do know, but just can't articulate it
then there's a wealth of general advice available on the 'net and, as I say, TSR offers a personal-statement-checking-and-improving service to help.
If you're having trouble finding out enough about the course, I might be able to get you in contact with some current students who you could pester to give you a genuine view of what it's like (I'm not a land economist myself, but know some) - PM me if that would help, but it's worth finding out as much as you can from more easily available sources - prospectus, websites, etc - first
Helpfully, if you're from Hong Kong, if you do decide to apply you're sure to get an offer as foreign students' fees are the only thing keeping universities here afloat at the moment (yes, I'm exaggerating, before anyone picks me up on this. I know what TSR's like, heh