Add installation and usage to README

README.md

@@ -1,2 +1,21 @@
 # Windows Auto Dark
-A program that sets/toggles the Windows 10 dark theme
+A program that sets/toggles the Windows 10 dark theme. This can be done with
+PowerShell, but it causes a window to show for a second. Running this program
+won't show a window at all. This makes it particularly useful for changing the
+theme automatically.
+
+## Installation
+Compile the program or download the executable from the Github releases page.
+Place the executable anywhere that users can access it.
+
+## Running
+If the program is run without any arguments, then it will toggle the dark theme
+setting. You can pass in one of two arguments: `light` or `dark`. Only the
+first argument will be read in, all others will be ignored.
+
+## Scheduling
+Use Windows Task Scheduler to run this automatically.
+[This article](https://www.windowscentral.com/how-automatically-switch-dark-mode-night-time-windows-10)
+has detailed instructions on how to do so. Just use the path to this program's
+executable in place of the path to PowerShell and `light` or `dark` in place of
+the PowerShell arguments.