It's hard to really explain how you can improve timing when using a tracker if you don't know how timing works in music, unfortunately. =/ However!
I recommend visiting
This site for a good solid introduction to music theory. For timing, pay close attention to the lessons on:
Notes and Rests
Measures and Bars
Time Signatures
Tempo
All of which go hand in hand.
Overall, however, this is actually pretty neat. You stay in the same key through out, and resolve a good majority of your progressions. It is consistant up until around half way through pattern 4, and with a little more knowledge on timing I think you could clean that up nicely.
When the choir comes in the harmonies work pretty well. What I really liked was how the choir went down in tone as the bells went up. I was surprised by it, actually, but in a good way.
What's most interesting to me is, again, to see the chord changes. (Though there are no actual chords played, you could definately hear what chords *would* be there). If I remember correctly you don't play any instruments, which is what makes me find that so interesting. Before I knew a lick of chord theory or much music theory in general, I relied on what I noticed in all the music I learned playing guitar of what chords work well together. I know that there are a tonne of talented artists out there who don't know anything about theory, so I'm not trying to say that you need to know theory to compose, you really don't. What I am saying is that from what I can gather, a majority (certainly not all) of those who compose meaningfull/good sounding, progressions, without theory knowledge, play an instrument of some sort. So to be able to just 'hear' that, is pretty impressive, whether you realised you did it or not.
Other than timing my most major complaint is the end note, it does not resolve at all. The run at the end is neat, and the holding the D note is good as it builds tension, but it also never releases that tension causing a strange feeling in my stomache I cannot describe. :P It's really a matter of preference and artistry, however, the way the end run is written, it makes me expect to hear another 'C' note to end the song.
In any event, I think you're off to a good start. No one's first tracks are masterpieces as it takes time, patience and practise to build up the skills those amazing composers/trackers have. I think it's great that you're actually trying to track now as I remember you saying that you had wanted to for awhile. You can't get better if you never start. :)
My advice to you is to go to your favourite mod place, download some good mods that you enjoy and open them in Modplug Tracker. Set the VU-Meters on (the button just to the right of Record button under the Patterns tab) to view what channels are currently playing a sound, and just watch them. Study the patterns, look at what samples are playing what, mute the channels and listen to some of the instruments inpendently to get an idea of things that work together, what generally plays what, what instruments compliment each other, etc.
But most importantly, compose, compose, compose. It's the best way to improve. :)