I'm currently on a student Visa right now, but need a business type, how do I get it?

So, I'm an international student right now and when my program ends I am going to Ningbo for an internship. Right now I am waiting for my business letter to arrive from the company I will be working for (which is to teach English). What materials do I need to present at the bureau and how do I prepare for it? Is there anything extra that I need to do? And, how much do I need to pay for this? And how long will the process take to get it? Thank you!