List C# add from List

//Declaring that its a list
List<string> test = new List<string>(); 
test.Add("Hello")var list = new List<string>();
list.Add("Hello");List<string> initialList = new List<string>();
// Put whatever you want in the initial list
List<string> listToAdd = new List<string>();
// Put whatever you want in the second list
initialList.AddRange(listToAdd);