i am british and my husband is nepali how can i apply for hongkong tourist visa for my husband?

Bina, he should first prepare the required documents including copy of his passport, the application form, a passport-style photo, flight itinerary, proof of his financial support, hotel booking record and travel plan to HK. And then post the application to HK immigration department to apply for it. The postal address is as follows:
Receipt and Dispatch Sub-unit
HK Immigration Department
2/F, Immigration Tower
7 Gloucester Road
Wan Chai, HK