how can i solve to handle the multiple html pages for e-learning website

i am making a e-learning website and its based on few coding langauges and im using pure HTML,CSS,JS no any other framework and all , due to newbie so i ahve a question regarding that lets say there an C langauge Page and if we take another example c has 20 concepts(ex) so will i have to make 20html pages and its css for all 20 concepts ? even if i input all the content of C in one page it will be chances of more loading of the page for user so please help anyone

im trying to make all the content in one html page so i can just manage 1html and css file and i was trying to do make 20 html page as i can make which is required for the content and lanaguages but it will take more time and i have to manage multiple of html and css file