Request for constructive criticism for Areledum

Okay, first let me say that you're on the right track. Musically, you're repeating the same sequence endlessly. To a lot, that can get very repetitive. I liked how you used the "Bass" voice to add intensity, but it doesn't build up more than that. You should have a little melody sequence that's changing to accompany this. What you've written is more suited for accompaniment.
When you're writing music, you should stick to the same general mood. You can switch moods, but make sure you switch via sections, not every measure.
Go ahead and keep tweaking the piece out. You can do it!

Also, a fun fact about organs, if you don't already know: much of the time, organs are giver THREE staffs, a treble clef, a bass clef, and a bass clef one octave down. This third staff is for the foot pedals, I think, but it might be fun to play around with a third, even lower staff.