Different themes will have different options, but most of them will end up under the Customizer.
To access the Customizer, go to “Appearance” > “Customize”. You can also click the “Customize” button in your admin bar if you’re on the front-end of your site.
Here’s an example of what the Customizer looks like:
It’s important to remember that each theme will have a different customizer.
What I recommend after you install a new theme is to go through all the tabs and set up your theme the way you like it!
Get familiar with your theme and its options, play around and try things. You’ll be able to preview your changes without publishing them. So play around, and if you like the way it looks, save your settings!
You’ll be able to upload your logo, a favicon, insert widgets, etc. via the customizer.