It could be said that Background MP3 Encoder works automatically. It monitors and checks a folder (or folders) you choose, so that, when a new WAV or MP3 file appears in that folder, the whole process is started.
That process in Background MP3 Encoder consists of codifying the files in that folder to another distinct folder you indicate, previously specifying the bitrate and the samplerate of the resulting files.
The Background MP3 Encoder user is the one who indicates the time desired for the monitoring intervals of the original folder (every 5 seconds, 15 seconds, every 2 minutes, etc).