documents i need from a company or organisation that employed me here in china

hi my name is johnson, i presently live in china, i have student visa and finally have gotten a job, i asked and was told that is not possible to convert student visa to work visa, so i need to travel back home or go to any nearby country, obtain a work z work visa on my passport and come back to china again, pls what documents does the organisation or company that employ me needs to give me and i can easily collect the work visa from the embassy.