how i can apply visit visa for Hong Kong i am Nepalese citizen on bahrain work permit visa

You can either submit the visa requirements to China embassy in Bahrain or mail it directly to Hong Kong immigration department to apply for Hong Kong visa.
Forms and Documents to be Submitted by the Applicants
1. Application for Entry for Visit/Transit in Hong Kong (ID 1003A)
2. The applicant's recent photograph (affixed on page 1 of the application form ID 1003A)
3. Photocopy of the applicant's travel document containing personal particulars, date of issue, date of expiry and/or details of any re-entry visa held (if applicable)
4. Photocopy of proof of the applicant's financial standing, e.g. bank statements, savings accounts passbooks, tax receipts, etc.
5. Photocopy of proof of transportation arrangement, e.g. flight itinerary
6. Photocopy of proof of the proposed leisure visit to Hong Kong, e.g. receipt of joining a package tour to Hong Kong, itinerary, etc. (for leisure visit only)
7. Other deemed necessary requirements by the embassy.

Forms and Documents to be Submitted by the Sponsor
(i) For application in which the sponsor is a Company:
1. Application for Entry for Visit/Transit (Sponsor) in Hong Kong (ID 1003B)
2. Photocopy of Business Registration Certificate

(ii) For application in which the sponsor is an Individual:
1. Application for Entry for Visit/Transit (Sponsor) in Hong Kong (ID 1003B)
2. Photocopy of the sponsor's Hong Kong identity card
3. Photocopy of the sponsor's travel document containing personal particulars, date of issue, date of expiry, and the latest arrival stamp/extension of stay label in the HKSAR (for non-permanent resident of the HKSAR only)