You have to learn it first. https://www.sololearn.com/learn/CSS/2253/
Abhisek jha you are on right path complete html first then css and then js. You can also learn html + css simultaneously. And then js. Keep patience . Read leasons. And practice daily. Don't make haste to do every in starting.wgen you will complete these thing it will be like much easy for you. If you however get these you can't understand as you have not completed basic. So better for you to go slow and practice the things you read everyday. In starting of html you can't ask about animation with js.it will not work for u. Hope you understand.