Thank you.
I really dont know how to answer you, but here are some tips:
Always start with the basic idea of the design by drawing on a paper. when your satisfied, open whatever program you can draw on the best. I use the Microsoft paint. Start with a circle for the wheel, and then start erasing and adding the curves of your design into it. When your done, start drawing the inside.
The whole thing would take you hours to look nice. be patient, and do not give up.
Then add colors and edit it with photoshop to give it a more realistic look. good luck

.