diff --git a/README.md b/README.md
index bb68ae1..810b712 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,7 @@ This mirror status checker determines whether CSC mirror is up-to-date with upst
 
 ## How To Run
 
-Run `main.py`.
+A configuration file may be provided through standard input. Without a configuration file, execute `python main.py`. By default, all of the available distributions will be checked. With a configuration file, execute `python main.py < name_of_config_file.in`, for example, `python main.py < example.in`. In this case, only the distributions listed in the configuration file will be checked.
 
 ## Resources
 
@@ -20,4 +20,4 @@ to find repos of the distros to check, just search "distroName mirrors"
 
 ubuntu releases: https://releases.ubuntu.com/?_ga=2.251394307.425973732.1629764407-1388600952.1629764407
 ubuntu mirrors: http://mirrors.ubuntu.com/mirrors.txt
-raspbian mirror: https://mirror.ox.ac.uk/sites/archive.raspbian.org/archive/
\ No newline at end of file
+raspbian mirror: https://mirror.ox.ac.uk/sites/archive.raspbian.org/archive/