c# 4.0 - Using StreamReader to get lines -

I would like to read a text file line from the line; I am using StreamReader

  streamer reader RDR = new streamrider (@ "D: \ testfile.txt");   
 How to read the file line from the line?   
 
 
 Use of  (streamer reader RDR = new stream reader (@ "D: \ testfile. Txt ")) {string line; While ((line = RDR. Redline ()) = null) {console.light line (line); // console to write}}