How do i find html & css open source projects to work on?

How do i find html & css open source projects to work on?

Are you asking where you can find projects to fork or clone to work on, on your own? Or are you asking how to find open source projects to give your contribution / become part of the dev team?
In any case html and css are front end markup languages hence, to see the front end source of a web page just use the inspector or dev tools of your browser.

Hi, i am a newbie over here and i know almost nothing about frontend development, i need a thorough guide here, i reallyhope i can get some help here. Thanks in anticipation.

As a paid freelancer or as an intern, learning and building?

For anyone that does not know how to open up the dev tools on a page, press f12 on currently opened page