You can get good information online from forums, but asking specific questions is always best, since there is simply so much
to learn, as with any field.
The best way to learn is to hang out at a barn. Take weekly lessons with a reputable
trainer (many aren't!) for at least a year, pick up what you can as you go along, read books, read web forums to supplement, and only after all that time should you consider buying a horse of your own!