First of all, are you the artist or are you allowed to use that image?
Cause it clearly says in the art's description do not steal.. But if you're the artist then ignore that ^_,^
All you have to do is right click on the image itself, click on "Copy Image URL" or depending on your operating system it might say something slightly different.
Anyway, once that's done, you follow the instructions posted in the tutorial above and type this:
[img]-<>-[/img]
Where I've typed -<>-, you paste the Image URL you copied earlier instead of that.
I hope I've explained clear enough XD
The link you've placed in you sig is the link to the page containing the image and many other things as well. That's why it wouldn't work XD
And the art is just fine! C:
Best of luck
Raphi