Saving your Animation as a .AVI file.
This can sometimes be a tricky task to do and can take a LONG time to render. luckily it should only be a 3 second animation and in AVI will be a small file. Its not like its got to render lots of detail now has it

this is a typical render formula to give u an insight to how long it might take
lets say u have 45 seconds of animation to render, playback rate = 15/s
each frame takes an average of 2 minutes to render due to detail
Total Rendering Time = 45 sec * 15 frames/sec * 2 minutes/Frame = 1350 minutes or 22.5 hours. =) enjoy that while it lasts.
Rendering a preview
on the Menu bar select "animation" and "make Preview"
just accept the defaults and choose "cinepak codec" from the drop down menu and click OK
Each frame gets drawn individually this shud take about 2 / 3 minutes in total and once its finished will open Windows Media Player with the animation in for you =) yay!
Rendering to a file
If you physically want to save the file then go to the "render scene" dialog by pressing F10 and select common parameters. change range from 0 - 100 and the output size at 320x240 ( under custom )
in the "render output" group choose "files" and find a location to save the file.
In the save dropdown list choose "AVI" file. and name your file
Once again choose Cinepak Codec and select your quality. and click ok
Back to the render scene dialog and click Render.
Once its finished rendering just find the render in the directory and open it.
there you have it. and here is the finished product.