How I get visa for China, Hong kong & Macaw for visit...?

My father doing Business and I also take-care my father business. Now I want to visit china for see great wall, it's a historical place and also see cubing city because it a flower city. Then I want to go Hong kong by road and see the electronic market such as photocopier machine, movie camera, computer accessories etc Because we have a Typewriter and photocopier machine business. We sell it retail and wholesale. We are importer New and second hand machine. For this reason I want to go Hong Kong for see the market. After complete work then I also visit Macaw by road. Macaw is a beautiful country, I saw it in discovery channel. Then I return Bangladesh. I just stay 4/5 days china, 2/3 days in Hong kong & 2/3 days in Macaw. Now my question is How I get invitation letter form there and which kinds of visa I need and where from I collect visa ? Thanks