I’m not going to go into a lot of detail here because hopefully, by now your site is already mobile-friendly. You can test your site out here to double-check if it is.
If your site is not mobile-friendly honestly, I suggest building a new website that is responsive. Simply put, a responsive website will visually respond to the size of the screen the user is using. If they are on a desktop computer, the site will look optimal for them. If they load the same site on a mobile device, it will “respond” and reorganize and resize content to make it look better on a mobile device.
StudioPress has some great WordPress themes that are responsive. If you are not willing to rebuild your website, you can always try a WordPress plugin that makes your website mobile-friendly as a temporary fix. Because I have never used any of them, I can’t recommend one to you but you can search for some on WordPress.org.