for sprite images, you can't post images until you have 15 posts. try posting in areas like the New Users/Welcome forum. I would just look around the main page and post in some different interesting threads. Once you do get 15 posts, use the [IMG'] [/IMG'] tags (w/out the ' marks) around a direct image link. You can also use the button that looks like a mountain with a sun.
By the way, welcome to PC! If you have any questions, especially about challenges , feel free to ask me.