Hey all,
I am a TOTAL noob in android coding.
SO I have to make this game...
The game is basically a 2D space invaders primitive clone.

There will be a set no. of enemies to shoot down that come towards you constantly.

I need to know how to do the following:-
1) Generate enemies on the screen at random positions at the top and make them fly towards the bottom
2) Make my player shoot bullets
3) make the enemies disappear if they touch bullets

If you have no programming experience at all, you can't really just jump in and start creating games. You'll have to learn some basic programming concepts first. Android uses Java so that would be a good place to start.

If you already have some programming experience and are just getting started with android you'll need to do some research on Android's core concepts such as Activities, Intents etc. Once you have a decent grasp of the Android application architecture and life-cycle then I recommend the "Playing with Graphics" tutorials here as a good place to start.

Good luck.