When you're in an oekaki, you click on the 'NEW TOPIC' button and wait. It'll take a few seconds to load on some computers. Then when it's done loading, there will be an art program there for you to start drawing. Note that in the Editable Oekaki, you can click on one of the images that some one did to make your own using that template. There will be a button below the picture that says some thing along the lines of: 'Make your own now!'. And after you are done one of your oekakis, you click on the 'Save' button and then on the 'Upload' button. It'll give you a few options to choose from there.
I hope that helped you! ^^ If you have any more questions, just feel free to ask!
