I am learning Html now and I want to become a front-end web developer should I learn Git and Github at the same time?
First, learning how to use GitHub is very good as you will have to use some kind of version control in your professional career. Learning how to use Git is even better, because it makes you understand GitHub in depth but since you're just starting, stick to getting a hang of GitHub first.
Second, learning HTML is a good start. If you're happy with how it feels, you want to look into CSS next. If you are feeling adventurous you can try to play around with advanced frameworks like reactJS. Most professionals are required to be able to work with those.
In general it's a good idea to consume a lot of tutorials, try them yourself and please: It's priceless to be able to work with the documentation provided for most software, programming languages and their packages. Just punch "HTML Documentation" or "reactJS Documentation" in your favourite search engine and it will take you to everything you need later on once you learned the basics.