How do i support a main idea in a introduction paragraph

you can start you main idea with what you're topic for example "why do you love your mom's cooking?" you're main idea would be you're mom's cooking but you would start your sentence this way "Why do you love you're mom's cooking? my mom's cooking is the best cooking because I found this in paragraph 2 of sentence 3.

all you would do is write about what happens, something that is in almost everything like for an example a main character is one.

Explanation:

another way to put it  in simpler terms: Is you could always re-read the text and see what happens, who is the main character(s), what is a word that appears a lot,

like for an example

My name is Kassie, I love to read but I have to read in secret because my foster parents hate books of any kind, I want to be able to read in public but instead I have to read at night, when I'm always tired from working everyday.

This tells you the main character, what she wants, the problem in the short story, and what the problem(s) is. also look at what she Said's  a lot(read) another example for your question!

the president was the speaker and it was a great part of history.

explanation:

video of the national aeronautic space administration's (nasa) coverage of president john f. kennedy’s address at rice university, houston, texas, concerning the nation's efforts in space exploration. in his speech the president discusses the necessity for the united states to become an international leader in space exploration and famously states, "we choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard."