Example:
public void foo(params string[] s) { ... }
We can call this method with:
a) foo(\"test\", \"test2\", \"test3\") //
Only the last parameter of a method can be a parameter array (params) so you can't pass more than one variable into a method whose signature only takes in params.
Therefore what you're trying to do in C isn't possible and you have to add that string into an array, or create an overload that also takes a string parameter first.
public void foo(string firstString, params string[] s)
{
}