You can make the letters line up by changing the font for that area to Courier New.

Just highlight the block of text you want to line up and then click the dark Tee ("T") (the second to last button from the right when creating a post) and select Courier New from the list.

I used the above text as an example of using the Courier New font. It's called a "monospaced" font meaning that all of the letters are the same width.

Hope this helps.