I just got CSS access and I’m pretty excited to add my own styling to my pages. What is the general way custom CSS is added?

When I opened it, I got a blank text box where CSS goes, what I expected to find was an editor that already had content in it. Do you need to explicitly type #wrapper or is your CSS automatically applied there? How do I find what the predefined classes are specifically?

It would also be helpful if someone can post a screenshot of their CSS to use as an example.

Edit: Figured it out

Thank you,