Press Space. ADDITIONAL TIPS: USE A REFERENCE. I cannot stress this enough. If you don't have every tribe's design memorized(I sure don't) use the official art as a guide. Of course, don't just trace the art, but use it to help you remember scale patterns, wings, head, and body shapes. Don't just copy my style, either. Experiment, try new things and make your own style. Don't get upset if it doesn't look right on your first try. The only real advice I can give is don't give up, and PRACTICE. Like, seriously, draw all the time. I'm not an expert, not anywhere close, but I've gotten as far as I have by practicing.
If you draw your own dragon, send it to me so I can see it! :)