do I need to apply for entry visa? if yes where can I get and submit the application?

Yes, you need it. You can submit the application to the Commisioner Office of the Foreign Affairs Ministry of the PRC. It is located on 3rd Floor, China Resources Building, No.26, Harbor Road, Wanchai, Hong Kong SAR.

The application documents include your passport, a photocopy of its data page, an application form, a bare-headed photo against a light background, the original and photocopy of your work certificate, and roundway tickets and hotel booking records.