Nikki,
I looked at your recent posts and saw that you tried it in the sandbox. Even though you had the pairing correct, I think, the reason it still showed up was because you had no text between the two sets of characters. Try finding a short post such as this one and quote it. When you do look at how the the characters are arranged. Below are examples. The word bold and the bolding marks beneath it were done exactly the same way I just did not have any text for the second example. The program just recognized them as characters and displays them that way. Maybe that will help.
BOLD
italicize
underline