Paje asks which course from the ones I'm offering should she first take? She has no prior history of formal music training except from singing with the choir since she was a child. She can barely read notes.
If you are in a similar situation like Paje, it's best to start practicing single voice melodic lines with one hand at a time. Rhythms should be very simple and slow at first. Perhaps whole-notes, later half-notes, then quarter-notes, eighth-notes and so on.
Don't forget to do the same with the pedals. Use toes only technique at first.
It's best to come up with both articulate legato and legato exercises in your practice. This way you can prepare yourself for both early music pieces (composed until 1800s) and later legato repertoire.
Oh, and by the way, try to explore a variety of keys too, not just those with zero or 1 accidentals.
If reading music of regular organ repertoire is too difficult for you, I recommend you start with my Organ Playing Master Course (Level 1). It's a 12-week course designed to help you advance your organ playing skills in a step-by-step manner.