lanbonese passport holder living in Doha. how to apply HK visa?

You should apply from Chinese embassy in Qatar. You should provide your passport, filled applicaion form for HK visa, a recent passport size photo, documents showing your purpose of visiting HK, invitation letter from yoru sponsor and other documents required by the embassy. If your application is approved by the embassy, it takes four working days to get it. If it is processed by HK Immigration Department, it takes around one month. By the way, you should pay for 20 USD for communication fee with HK Immigration Department.