I'm sympathetic to you being a beginner to flash making, and I'll try not to be too harsh on something you obviously put some effort and time into making.
First off; try to make your menu screen a little more legible. Until you become adept at using stylized script, trying just using good old print, nothing wrong with that! I found it hard to read some of the instructions because they were written in cursive, and some of the text throughout was a little hit and miss in my opinion. Also, try to be more clear in your instructions (I.E. To avoid being shot/hit by harrier bomb, point gun behind barrier.) A lot of the game play was off as well; For example, the bomb at the beginning is impossible to hit, sprayed it several times with no effect, merely a game over. Try getting enemies to switch up attack routines, instead of always scrawling from the left side, it became repetitive motion of; Kill bad guys on screen, duck to avoid being shot by off screen bad guys, kill bad guys, reload, etc. (Also, there is never any additional harriers?)
The actual art was lackluster overall, but with improvement could be decent.
Pros: Controls are simplistic
"Pick up and play" (No learning curve)
Multiple sound tracks + No loop over flash
Cons: Game play uneventful
Somewhat vague instructions
Very simplistic game
Sound effects repetitive/annoying
Script sometimes illegible
Visual quality overall sub-par
Remember; never give up! Becoming a good flash artist is a series of trial and error, and learning from your mistakes. Perhaps some of your friends could help you with the art as well? Collaboration is a great way to make some quality flashes! I look forward to more flashes from you in the future!