Check List For a New Website
Delete the default page, post and comment that come with every new installation.
Go through each of the subheadings under 'Appearance' and make the appropriate modifications, updating or saving changes as you go. Don't touch the 'Editor'. If you want to make changes to your theme then make a child-theme. You'll find lots of information on https://wordpress.org/search/child+theme. You may need to login to wordpress.org first.
Under Users > Your Profile write something in the 'Biographical Info' section. This may appear on your blog in some themes.