That's it. That's all that is written, there ain't no more.
The Discordian Wiki was not particularly enlightening either. Although, I am marginally reassured to read that, "St. Tib is not a cabbage." But, a very little research (I googled "St. Tib.") leads me to believe our holy St. Tib's Day has it's origin in old Tibb's/Tipp's Eve, and Saint Tibb/Tib memes.
Getting back to our own hallowed Principia Discordia, I believe our own St. Tib is a Lieutenant Saint, since he/she doesn't appear to have much of a following. But, I assume he/she could be promoted to Brigadier Saint some leap year, if he/she ever takes an interest in establishing a following. Further, because of this leap year thingy, I suspect St. Tib is our patron/patroness saint of "interrelation" (timekeeping). And, as timekeeping is an orderly, aneristic activity, it seems an interesting thing for a Discordian saint to do. But, such is the nature of Discordianism.
So, based upon the old memes, I think the best way to celebrate St. Tib's Day is to honor him/her by pouring out an intoxicating libation, as per the sacred ritual practiced by the ancient Greeks, and tippling back, at least, one in his/her honor.