1. Login to your WordPress Admin Dashboard.
2. In the sidebar, hover over Appearance and click Themes.
3. On the current theme, click Customize.
You’ll be brought to the Customize page, where you’ll see a new Sidebar on the left with your website preview on the right. The options present in the Sidebar vary depending on the theme you’ve chosen, but they usually have General, Header, Site Identity, Widgets, and Menus. More advanced themes often let you customize more sections with more freedom.
All themes usually allow you to add your own CSS, so this can come in handy to do certain adjustments that the theme doesn’t support natively as an option if you know your way around CSS.