Hi there Robert. Can you please confirm that English is your native language? Or maybe you can speak in other languages as well?
Basically, when somebody who speaks Chinese and wants to learn English sees your post, he or she responds. Then you exchange contact details and arrange audio or video (via Skype or similar software) lesson.
You will teach them English, and they will teach your Chinese. Of course this can be just casual conversations in both languages not formal lessons.
Because or website is not too popular, you can also check other places dedicated to language exchange. Here are some links: