To add strings in string array

Question

hello, i am doing a project which processes the log file and takes a line, splits to an array of strings. thats working. but simultaneously i need to add a detailed string which is part of the line(taken from the log file) into a string array. how can i add the string to an array. can i use insert? but an error occurs when try to add the string in an array. the error is "Object reference not set to an instance of an object. can u help me. thank u, gayathri