First, let us ask ourselves who are these people who should be practicing this feast of Puriym? 

Additions to Ecster (Esther) 5:8

There is a certain people scattered abroad and dispersed among the people in all the provinces of your kingdom; and their Torah is diverse from all people;

The people scattered abroad and dispersed among the people in all the provinces were of course the whole of the house of Yisra’el, all of the twelve tribes, for the Northern Kingdom had come into captivity in this region after its destruction in 722 B.C., and the Southern Kingdom had come into captivity at the time of the destruction of Shalomah’s temple in 585 B.C. These were the people who had a Torah which was diverse from the people of the kingdom, whose laws were the laws of the kingdom, and not the Torah, the commandments, the statutes, the ordinances, and the judgments of YAHUAH. 

Ecster was the queen in Shushan, which was the chief city of the Medo-Persian Empire, an empire that at the time spread from India to Kush (Libya). This empire followed the Babylonian Empire, which followed the Assyrian Empire, which followed the Egyptian Empire.  The house of Yisra’el was spread in a diaspora among all of its provinces, but the people did not forsake the Torah of YAH. 

Consider Mordekai’s prayer:

Additions to Ecster (Esther) 7:18

18 Then Mordekai thought upon all the works of YAHUAH, and made his prayer unto him, 19 Saying, O YAHUAH, YAHUAH, the King EL SHADDAI: for the whole world is in your power, and if you have appointed to save Yisra’el, there is no man that can gainsay you: 20 For you have made heaven and earth, and all the wondrous things under the heaven. 21 You are the YAHUAH of all things, and there is no man that can resist you, which are YAHUAH. 22 You know all things, and you know, ADONAI, that it was neither in contempt nor pride, nor for any desire of glory, that I did not bow down to proud Haman. 23 For I could have been content with good will for the YAHUSHA of Yisra’el to kiss the soles of his feet. 24 But I did this, that I might not prefer the glory of man above the glory of ELOHIYM: neither will I worship any but you, O ELOHIYM, neither will I do it in pride. 25 And now, O YAHUAH ELOHIYM and King, spare your people: for their eyes are upon us to bring us to nought; yea, they desire to destroy the inheritance, that has been yours from the beginning. 26 Despise not the portion, which you have delivered out of Mitsrayim for your own self. 27 Hear my prayer, and be merciful unto your inheritance: turn our sorrow into joy, that we may live, O YAHUAH, and praise your name: and destroy not the mouths of them that praise you, O YAHUAH. 28 All Yisra’el in like manner cried most earnestly unto YAHUAH, because their death was before their eyes.

Those who adhere to this Torah while being dispersed throughout all the nations are the people who are called to practice this feast of Puriym.

Then we will ask ourselves the question: How does one go about it?

First, there is the fast:

Additions to Ecster (Esther) 7:16

Go, gather together all the Yahudiym that are present in Shushan, and fast ye for me, and neither eat nor drink three days, night or day: I also and my maidens will fast likewise; and so will I go in unto the king, which is not according to the law: and if I perish, I perish.

Then there is the practice of the feast itself:

Additions to Ecster (Esther) 14:19-32

Therefore the Yahudiym of the villages, that dwelt in the unwalled towns, made the fourteenth day of the month Adar a day of gladness and feasting, and a good day, and of sending portions one to another. 20 And Mordekai wrote these things, and sent cepheriym unto all the Yahudiym that were in all the provinces of the king Achashverosh, both nigh and far, 21 To stablish this among them, that they should keep the fourteenth day of the month Adar, and the fifteenth day of the same, yearly, 22 As the days wherein the Yahudiym rested from their enemies, and the month which was turned unto them from sorrow to joy, and from mourning into a good day: that they should make them days of feasting and joy, and of sending portions one to another, and gifts to the poor. 23 And the Yahudiym undertook to do as they had begun, and as Mordekai had written unto them; 24 Because Haman the son of Hammedatha, the Agagiy, the enemy of all the Yahudiym, had devised against the Yahudiym to destroy them, and had cast Pur, that is, the lot, to consume them, and to destroy them; 25 But when Ecter came before the king, he commanded by letters that his wicked device, which he devised against the Yahudiym, should return upon his own head, and that he and his sons should be hanged on the gallows. 26 Wherefore they called these days Puriym after the name of Pur. Therefore for all the words of this letter, and of that which they had seen concerning this matter, and which had come unto them, 27 The Yahudiym ordained, and took upon them, and upon their seed, and upon all such as joined themselves unto them, so as it should not fail, that they would keep these two days according to their writing, and according to their appointed time every year; 28 And that these days should be remembered and kept throughout every generation, every family, every province, and every city; and that these days of Puriym should not fail from among the Yahudiym, nor the memorial of them perish from their seed. 29 Then Ecter the queen, the daughter of Aviyhayil, and Mordekai the Yahudiy, wrote with all authority, to confirm this second cepher of Puriym. 30 And he sent the cepheriym unto all the Yahudiym, to the hundred twenty and seven provinces of the kingdom of Achashverosh, with words of peace and truth, 31 To confirm these days of Puriym in their times appointed, according as Mordekai the Yahudiy and Ecter the queen had enjoined them, and as they had decreed for themselves and for their seed, the matters of the fastings and their cry. 32 And the decree of Ecter confirmed these matters of Puriym; and it was written in the cepher.