Do you mean
oekaki? Once you've chosen a board (beginner's oekaki is probably best choice if this is your first time drawing in oekaki), you can start drawing by clicking on the "new topic/new drawing" button. Make sure you have
Java installed! :] For further instructions, check
here or
this guide.If you have other drawings to share, you can make a topic for them in
share your art. If the picture is on your computer, you need to upload it to a site like
Photobucket or
Tinypic.