It seems to me that you are trying to refer to what Windows calls SpecialFolderConstants (or sometimes referred to Common Folders). However, not all of these are available as environment variables (as you mentioned %APPDATA%
).
See these links to get further information
To get a list of your environment variables and check which common folders are defined as variables you can use PowerShell and run
cd env:
dir
You could place something on the user's desktop by starting with something like this:
var path = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
However, for creating desktop shortcuts, your question might already be answered by Create shortcut on desktop C#
.