Hii!
To become a teacher of chemistry, the first step which you need to take, is to do BSc in chemistry. Then, you can go for further studies such as MSc chemistry and even PhD if you aspire to.
However, you will need to obtain teacher's training lisence. Meanwhile, you can apply for teaching jobs in schools and colleges on a contract basis. Once you complete your degrees essential for teaching, you can apply for a permanent teaching position in a firm of your choice.
Hope this helps.
Good luck!