What documents do we need to submit at your office for the Visa process?

I am visiting during 15 - 23 May '13 to participate in China Trade Fair program of NATTA (Nepal Association of Tour & Travel Agents). So what are the documents do I need to provide at your office for the Process. It will be very kind of you if you reply my email as soon as possible.

Thank you.

Best Regards,

Prabhat Manandhar