TextBox Lists--Alter the second text box string

Hi guys-
I am a beginner in C#, and I am writing a very simple application.  I basically want two text box's, textBox1, and textBox2.  The user writes a list in textBox1, and the list is displayed with some formatting in textBox2. 

12345667         '12345667',   
12345668         '12345668',
12345669         '12345669',
12345670         '12345670'

I have tried a number of different ways.  My biggest hope was putting txtBox1.Text in a string, and splitting it with a regex of ("\n").  I thought it was going to work, but when I do that Regex, it does not remove the "\n" so I cannot add ' right after the split string.  Instead it looks something like this:

'12345667
','12345668....

Can someone write me a small code example of an effective way to take the list out of the left text box, format it, and display in text box 2? 

Thanks guys!
Stephen