Newbie CSS positioning/mapping

I’m currently running a wordpress theme and i’m trying to implement typed.js I succesfully installed and now stuck with the css part of it.

As you can see in this screenshot: https://prntscr.com/cjyu55 i’m tryng to position it properly… But everytime i’m doing changes on that section, the whole page changes too so i need a solution to make just changes for that part of the typed.js section on the header…

Im a noob in those things but if someone could explain how i can make another section to just edit the typed.js i would really appreciate that.

Thanks