Tuesday, Feb 15 is Purim Katan. The last section of the Shulchan Aruch (697) is about Purim Katan.
The Shulchan Aruch says:
On the 14th and 15th of the first Adar one should not say Tachanun and should not say the Psalm, La-Menatzeyach Ya’ancha Hashem Be-Yom Tzarah. One these days we don’t say hespeds or fast. However, other Purim matters are not practiced on them. There are authorities who say than even hespeds and fasts are permitted on them. The Rema says: The practice accords with the first reasoning (i.e. no hespeds or fasts)
The Rema adds: There are authorities who say that one is obligated to increase ones feasting and rejoicing on the 14th of the first Adar. This is not the practice. Nevertheless, one should have a somewhat larger meal then in order to satsify the view of the authorities who are stringent in this matter and someone with a contented heart is always festive.
The Mishnah Berurah says: The Tashbeytz stated that one should have a larger meal on Purim Katan and Rabbeinu Yechi’eyl of Paris was accustomed to have a larger meal and invite people. This is what the Rema means when he concludes by saying “and someone with a contented heart is always festive” i.e. that it is desirable for one to have a larger meal to honor the miracle which was performed at these times.
As it happens, this week concludes the 7 year cycle of the Daf Yomi B’Halacha cycle which goes through the entire Shuchan Aruch and Mishnah Berurah with a 5 day a week learning schedule. The new cycle begins on Sunday, February 20.
Sefaria has begun an English translation of the Mishnah Berurah.
YU Torah has shiurim on the Mishnah Berurah cycle.
The OU has has shiurim on the Mishnah Berurah cycle.
This is probably the most important Yomi cycle since we need to know halacha to serve Hashem properly. This is a great opportunity to going through the Mishnah Berurah. Please join the cycle this upcoming Sunday.