an attempt to clarify monitoring vs searching when adding a show.

Setup-Guide.md

@@ -89,6 +89,20 @@ You want to enable this and you *don't* want to use the Drone Factory option. Th
 * Folder renaming isn't working. _Planned to be supported_
 
 * Subtitles and other files aren't moved with the movie. _Planned to be supported_
+
+## Two kinds of search methods: historical vs monitoring
+
+Radar has two search methods: historical and monitoring.  Monitoring identifies releases occurring after monitoring starts.  Historical search finds previous releases.
+
+Monitoring is enabled by toggling a banner icon, where a solid banner indicates monitoring is enabled. 
+Historical search is invoked by clicking the magnifying glass icon.  
+
+If you only enable monitoring, Radarr will only download releases that occur after monitoring is enabled.  
+
+When the magnifying glass icon is clicked, a single historical search is stared; however, the historical search is filtered to include only monitored episodes. So, monitoring of the show, season or episodes must be enabled first, before historical search.
+
+In other words, after you add a show to Radarr, first toggle the banner to select either show, season or individual episodes, and then click the magnifying glass to start a historical search for those selections.
+
 ## Misc
 
 * We use [The MovieDB](https://www.themoviedb.org) for gathering information. Sometimes a movie in IMDb is not TMDb, please help by contributing to TMDb and the movie will then show up in Radarr Movie Look up.