How to comment multiple lines with space or indent

Pressing Ctrl+K+C or Ctrl+E+C After selecting the lines you want to comment will not give space after slashes. you can use multiline select to provide space as suggested by Habib

Perhaps, you can use /* before the lines you want to comment and after */ in that case you might not need to provide spaces.

/*
  First Line to Comment
  Second Line to Comment
  Third Line to Comment      
*/

One way to do it would be:

1. Select the text, Press CTRL + K, C to comment (CTRL+E+C )
2. Move the cursor to the first line after the delimiter // and before the Code text.
3. Press Alt + Shift and use arrow keys to make selection. (Remember to make line selection(using down, up arrow keys), not the text selection - See Box Selection and Multi line editing)
4. Once the selection is done, press space bar to enter a single space.
   

Notice the vertical blue line in the below image( that will appear once the selection is made, then you can insert any number of characters in between them)

I couldn't find a direct way to do that. The interesting thing is that it is mentioned in the C# Coding Conventions (C# Programming Guide) under Commenting Conventions.

Insert one space between the comment delimiter (//) and the comment text

But the default implementation of commenting in visual studio doesn't insert any space