There is no requirement that you both declare and fill a string at the time of its original declaration, but there is no reason not to do the complete task in one place:
string[] strBunchOfStrings = new string[] {"Somewhere", "Over the Rainbow", "Way up High", "There's a land that I've heard of"};
The operators used to manipulate the contents of strings are discussed in Chapter 10, String Manipulation and Online Data Storage (Arrays).