Here's a video: https://youtu.be/FwsV5PyWOAo
To sign in to a self-hosted WordPress site, please open the app and tap on "Log In". Then, select the "Log in by entering your site address".
This will add another field to the form so you can enter the site's address (domain name or URL) of your site. You can then login with your username and password, the ones you use to log when using a computer browser.
If you are already logged into a site in the app and you want to add another self hosted site, go to My Sites and click on the + button, then select the link to 'Add self-hosted site.' For this option, enter the username, password, and URL associated with that site.