It's very easy to use them, once you know how - just copy the line of code... and change the colors from the word "yellow" to the other colors.
For instance this picture is done by putting in this line of code into the sentence:
<img src="http://tinyurl.com/yellowhaticon"/> Don't change any of the spaces or the characters, or it won't work. Make sure you copied the whole line, including the <>s. When you're posting, you can check to see if it worked correctly by hitting the "html" button in the top of the text box, (the last button.)
With the Blue hat, you have to add the number 1 after the word "icon" So for this: you would need to copy this into the line that you're writing: <img src="http://tinyurl.com/bluehaticon1" /> in the line.(Don't worry if the line of code breaks in another line, (as it just did here.) It will still work if you haven't changed anything.)