Second Tithe and Tithe for the Poor
Question
This question revolves around the Second Tithe and Tithe for the Poor summarized in Deut 14:22-29.
For the sake of clarity, let's assume we live in the Land.
In Deut 14:22-27, the Torah indicates that every year of the 7-year shemittah cycle, we should observe the Feasts (Pesach, Shavuot, Sukkot) in the place G-d chooses i.e. Jerusalem if residing in the Land.
Deut 14:28-29 is unclear on how one is to use their Festival (Second) Tithe and go to Jerusalem each year and how to distribute the Poor Tithe in Years 3 and 6.
I've searched the Mishnah and other sources but could not find any real-world examples of how this was done and how we could use the principles for observing the Feasts and Tithing to the Poor in Years 3 and 6 today.
To summarize the Question:
During the Maaser Ani years, if the tithes were given to the poor, how did the pilgrims pay for their travel and eat when they went to Jerusalem? Or, is the Poor Tithe an additional tithe aka Third Tithe in Years 3 and 6?
Any resources that would help explain how this was applied would be greatly appreciated as I am working on a Teaching on this subject.