In English, "from" is used to indicate an origin or to express "from--to". "I am from San Diego", "She worked from 10:00 to 11:00.
Using "of" in English usually indicates possession. "He is a friend of mine", "They are the leaders of the troop."
"Of" is also used with "all" or "both": "Do you have all of the money?" "I know both of them."
"Of" is also used to express a superlative: "He is one of the the most generous persons I know."
There are a lot of good websites on the Internet for a more in-depth discussion and practice.