Not sure what you mean by premium channels. Movies and series are not in any channels. On the left sidebar or down the bottom when you open Stremio you will see Board, Discover Library Addons and settings for the landing page on mobile devices like Tablets and for the side bar on Streaming devices hooked up to your TV you will see Search at the top, then Home, Discover, Library, Addons and settings. Now on a streaming device click the Discover and it starts off on the Movies page. Scroll right and you will see movies under the :Movies : Popular : Default you can click on any movie to open ot and if you have addons installed you will find it shows a source for you to choose and play. If you click up once it will highlight the three choices I listed. Click the OK buttons and that begins by starting you off on your selections. Click down once and series will begin to show. Click right once to open choices and then right for more choices in either Movies or Series. Now if you want to add a series to your library click ok to set your choices you made in the options then it starts at the far left and you click right to scroll through your choices. Long press OK on any Movie or Series to open a popup that will give you details to click ok on or click down once to highlight Add to Library and click ok to add it. That is just a start.
You can use the search for other threads and watch Troy’s vids as well as read some manuals.