Hague Service Convention comes into force when the documents are to be served upon a party to the litigation, living in another country, which is also a signatory to the convention. The treaty contains various provisions regarding service of judicial and extra-judicial documents in civil matters. You need to approach the Central Authority appointed by the government of the country where you have filed the legal case. You will have to submit the documents to the Central Authority along with the fee and the form prescribed by the authority.
The Indian Government has appointed the following agency as Central Agency for Hague Service Convention India:
Department of Legal Affairs, Ministry of Law & Justice, Shastri Bhawan, New Delhi 110001