Start Plex on your computer if it’s not already running.
Open the media manager. If you’re using Windows, start Plex, then find the Plex icon in the bottom right part of the task bar (a yellow arrow on a black background), right-click it, then click on “Media Manager.” If you’re using a Mac, click on Launchpad to access the Plex icon, then run it (according to this video). You’re on your own for Linux.
The Media Manager will open up in your default browser; Plex does pretty much everything through the browser. The first time you start the media manager, you will be sent to a set up wizard which will allow you to name your server and set up your library.
Whether you use the wizard or set up your libraries later by clicking on “add a section” in the main page’s “My Library” box, you will be asked to choose whether this section is for “Movies,” “TV Shows,” “Music,” “Photos,” or “Home Movies.”
This will determine what files show in that library section. Even if you have a single folder containing all your media, your Movies folder will only find and show movies, your TV Shows folder will only find and show TV series, etc. If the Plex media scanner doesn’t recognize the naming convention (usually, for example, TV series need to be named something like “Go.on.S01E05.HDTV”) then it won’t list the video in that section.
The Home Movies category, on the other hand, shows all videos in all folders specified, regardless of title; so a Home Movies section creates an easy way to access videos you don’t want to bother renaming.
After you choose a category, add one or more folders that contain your media. If you’re using Windows, be warned that the “browse folders” interface won’t show “My Documents” on the top level; you need to know how to navigate the Windows file folder structure to find the file you want. Alternately you can just create a media folder in the C: root drive.
After adding sections, Plex will scan the folders and add the appropriate media to each section, attaching descriptions and images and other details. This can take a while, so wait until there’s something in your library before you go on to the next step.