C# – where should I place the DLL file when I use dllimport?

I know that in Windows Forms, you only need to put files in the debug folder, but it seems that it is completely different in Android monodev. I have tried to place files from the assets folder, add reference paths, and reference folders from project settings, but I still have no luck. I always get a dllnotfoundexception

In addition, the following is the code to import the DLL file

[DllImport("testing.dll", EntryPoint = "Testing_Open", ExactSpelling = false, CallingConvention = CallingConvention.Cdecl)]
 public static extern uint Testing_Open(HINSTANCE hInstance);

resolvent:

You cannot use dllimport. DLL on mono for Android because it is a Linux based system, not a Windows based system. You need dllimport a Linux shared library (*. So)