css advice??

hiii so i'm trying to set up my profile and i'm new to css, (only know html) i've seen really cool pages do this, does anyone know how i can code this half of the page to just be a simple be black with white font?
edit: i've tried copy pasting from just messing with the inspect element where i originally coded it to look like what i described but it didn't work when i pasted it in so i'm assuming it's something different entirely ^^;
https://cdn.discordapp.com/attachments/717447492370694175/758788731003731978/unknown.png

also in the "About Me:" section how would i separate my lines? is there something similar to <p> for css? would i put that into the customize section or would i paste the code into the actual about me section? would it be the same for images?

thanks so much!!