we wanna marry but....

hi,
i got a british passport and wish to marry a girl with a BNO passport hopefully.

do i need to go with her to her country of residence to marry here there or do i have to go just to get a certificate of approval or something?.
she is from hong kong, and born there.
whats the procedure, and who do we contact in hong kong to arrange/find out more?.

we are hoping to go in the next coming months.
she is in the uk with me.

thanks.

OK, so she is in the UK at the present time .... on what basis? As a visitor? Or if she has a visa in her passport, what sort of visa? And when issued, what was the length of time that visa was issued for?

It would also be worth knowing if this girl is also a Chinese citizen (ie, ethnically Chinese) or not.