How to send input string to console created by AllocConsole() in C#?

How to send input string to console created by AllocConsole() in C#?

I'm tring to WriteConsoleInput to a Console app after I use AttachConsole.
I don't know where to get the HANDLE definition
I need the definition of HANDLE to do something like this:
HANDLE rHnd;
rHnd = GetStdHandle(STD_INPUT_HANDLE);
WriteConsoleInput(rHnd, );
I would just like to write some characters to the console input buffer,
but this is proving difficult, if you have any direction, definitions,
examples, et cetera, I would appreciate it very much.
Thanks.