is there any tool on net where i can teach online to students without any fee ??

Now it depends on whether you would like to start a coaching website of your own or work as a tutor for other sites. There are many sites which would provide such coaching jobs. If you want to start a site of your own, you can do it free of cost. You can also assemble tools so as to help you with it. Now it requires creativity & research. Happy Lotting