In Webflow you first design your website for desktop devices and then make changes on mobile devices (access the Device icons in the top bar). Adding styles in a mobile device will override the desktop styles.
You got it! There are tons of people learning Webflow and web design every day. A great place to start is the video tutorials. Then head on over to the support center or community forum.
(You can click on the links above by going into Preview Mode – the eye icon in the top left corner)