This is the Zakat section, with lessons on the obligatory charity. There are six pages.

What Is Zakat explains its meaning, its place among the five pillars, and how it differs from voluntary charity. Nisab, Hawl and the Zakat Rate explains the threshold, the year, and the rate of two and a half percent. Two lessons cover zakat on gold, silver and jewellery, and on cash, business and investments. Who Receives Zakat explains the eight categories of recipient named in the Qur'an. And Zakat al-Fitr covers the separate charity given at the end of Ramadan.

For a quick figure, the Worship page has a simple Zakat estimate for money and trade goods. If your situation is complex, confirm the result with a scholar.