As a first try, this is not too shabby... However,

I agree, this is very piercing to the ears.... Quiet things down a whole bunch, and you'll have a much listenable song. This melody kinda jumps around too much, there is nothing really tying it all together, so as a result it sounds kinda random... Work with having a general theme, idea, or motif work the piece towards a logical conclusion (or if you are so inclined, and ILLOGICAL conclusion). In short, not bad for a first attempt, but keep on experimenting, trying things out, and all that other good stuff on the path of audio production.

Advice for FL
Also, experiment with the filters in FL, as they can really add some cool effects to your songs.

Look around for some good samples too. Good soundfonts can really make your songs come alive, much more so than the stock FL stuff.

Not bad.

The first thing that hits me is that the melody is very VERY high picthed and really stings in my ears, but other then that, i really like the melodies.
I've never used FL studio, so i can't say anything on that, but when the main riff kicks in at 1:06, i'm completely diggin it.
The overall structure of the song seems a bit messy, and it doesn't really have a natural flow to it, but i still think it's a good song.