What should I do to apply for a patent?

You can apply for a patent. After you get the patent number, you can search all over the street to see who is using your method. You can directly take out your patent certificate and tell him that it is infringement, and ask him to give you the royalties. If not! Just sue him and let him compensate you for your economic losses. If not, you can search Baidu: Ren Wenlin, and see how he defends his rights. He has the most patents in China.