Well..
Your graphics really aren't too bad, but there are some areas you can easily fix. For example, don't use plain white circles as stars. Try checking out radial fades in Flash. And the fire: instead of just having the two frames moving every second, make a few more frames, and have them going faster.
This probably won't get through the portal, but don't let that get you down. Improve on little things like I said, and continue on with this idea. Also, try a faster frame rate. 20-25 ain't a bad idea. You may have to work more, but it'll be a lot more smoother. :)