What should I do to achieve more in developing?

Question

I am a student of O Levels. I recently developed interest in coding. I learned html and css to a great extent. I am not a pro but yes I can create static webpages and style them efficiently. I made a form page including several input tags. What should I learn more? I searched and founded different opinions on python, JavaScript or java etc but I myself feel that JavaScript will be more beneficial as it will allow me to create a dynamic website. Is this right or should I learn any other language. Moreover how much time it will take to learn all basics?