C# add to array

Question

In a C# 2008 application, I need to be able to add records to a string array once the string array has been setup from the code listed below. 
  string[] Files = Directory.GetFiles(strFullpath, "*pdf")
                                                                 .Select(path => Path.GetFileName(path))
                                                                 .ToArray();

Thus once the   string[] Files hae been setup, can you tell me how to add more records to the Files array of string[] objects?