Thailand embassy has out sourced their business to VFS global. Please do a google search for vfs global Thailand visa. You would need to visit their office on Delhi or Mumbai.
Ask your boss to go to immigration and ask for the non b visa check list. Get all the documents and then apply for non b visa. The non b visa will for 3 months. Try to get your work permit in the first month and then your 3 months visa will be extended to the next 9 months or more. Most important thing is the wp3 letter which your boss has to get from the employment office in Chaing Mai.