An Indian Living in El Salvador, Central América. Need a 'M' visa

Sambit, you need to prepare those documents containing your passport and copy of its data page, the application form attached with a recently-taken passport-sized color photo, your residence permit in El Salvador, as well as an invitation letter from your trade partner in PRC, round trip air tickets and hotel reservation.
And then submit your application to the consulate general of PRC in Rio de Janeiro to apply for the M type.

It usually takes 4 working days and costs R$13,000.