I found a very easy to understand summary of Zakatul Fitr for you:
WHAT IS SADAQA AL-FITR?
Sadaqa Al-Fitr (also known as Zakatul-Fitr) is a small amount of food to be given in charity at the end of Ramadan, before the holiday (Eid) prayers. This charitable contribution is separate from the annual payment of Zakat, which is one of the pillars of Islam. Unlike Zakat, which is calculated annually as a percentage of extra wealth, the Sadaqa Al-Fitr is to be paid equally by every Muslim man, woman and child at the end of Ramadan.
THE SADAQA AL-FITR TRADITION
According to the Prophet Muhammad (Sallallahu Alaihi Wasallam), each person should give away in charity an amount equivalent to one sa'a of grain. A sa'a is an ancient measure of volume, and various scholars have struggled to interpret this amount in modern measurements. The most common understanding is that one sa'a is equivalent to 2.5 kilograms (5 pounds) of wheat. Rather than wheat grain, each individual Muslim--man or woman, adult or child, sick or healthy individual, old or young family member--is asked to give away this amount in a non-perishable food staple, which may be a food other than wheat. The senior member of the household is responsible for paying the amount on behalf of the family. So in family of four individuals (2 adults + 2 children of any age) the head of the household should purchase and give away 10 kilograms, or 20 pounds, of food.
It is recommended that the Sadaqa Al-Fitr be given as an amount of non-perishable staple food, not cash.
The purpose of this charitable donation is to ensure that all members of the community have food to eat after Ramadan and during the Eid holiday. The recommended foods may vary according to local diet, but traditionally include:
Flour/Wheat
Rice
Barley
Corn
Dates
Raisins
Some scholars advise that donations of cash are permissible if one is living in an area where food is readily available for purchase.
However, most scholars agree that giving food products is preferable.
Source:https://www.thoughtco.com/how-much-is-sadaqa-al-fitr-2004612
In USA it is $10 per person which you must pay before Eid prayer.
You can give to any good reliable online Islamic charity in the US.
And Allah knows best in all matters