http://serviio.org/component/content/article/10-un categorised/5-getting-started

Adding content to Serviio's media library

Open Serviio console by clicking on the system tray icon
Select the Shared folders tab
Add folders that include media files you want to include in the library and pick what type(s) of media files from those folders should be looked for (Video (), Audio (), Images ()). You can specify if descriptive metadata (e.g. online metadata, XBMC, Swisscenter, MyMovies) should be retrieved for video files in particular folders (), which might be useful to control, for example, metadata of your home videos. You can also choose whether a particular folder should be monitored for future file additions/removals/updates (), which is handy for removable or static media repositories.
You can also add online resources to the library
You can fine tune access to the shared content
Click the Save button when you are done.
The library will now be updated and then again automatically when Serviio looks for added files (by default every 5 minutes).
Note that when you add a large amount of files (e.g. during your initial setting up) it might take cosiderable amount of time (even several hours) to properly locate metadata for all your files (especially if you are using online sources for metadata searching).
You can force checking for new or updated files (without waiting for the automatic check) by clicking "Force files check" button.
get more information on the wiki