It’s been a while since I used python, but I remember being able to access everything stored in an array by doing the following:

 array[0:]

having the colon after the zero meant you want to reference everything stored in the array. How would I go about this in C#?

That’s just syntactic sugar.
To know my knowledge, nothing like that exists in C#.

You can use a foreach loop:

int[] numbers = {4, 5, 6, 1, 2, 3, -2, -1, 0};
foreach (int i in numbers)
{
   System.Console.WriteLine(i);
}