日本語では伝聞話法と言っても特別難しいことはないでしょう。
英会話となるとこの伝聞話法が良く出てきます。
人が話すのを伝聞の形で話す時には
ちょっとした英文法のルールを使います。
受験勉強のようですが、パターンを一応覚えましょう。
直接話法 伝聞話法
１．現在形 過去形へ変更
She wears a red coat. He said she wore a red coat.
２．現在進行形 過去進行形
I am looking for my car. He said he was looking for his car.
３．現在完了形 過去完了形
She has finished her work. He said she had finished her work.
４．過去形 過去完了形
He gave me a book. She said he had given her a book.
５．will would
I will complete this in a day. He said he would complete this in a day.
６．can could
I can speak French. She said she could speak French.
７．must had to
I must go to the post office. He said he had to go to the post office.
直接話法と間接話法すなわち伝聞話法では時制にの変化が生じます。
そのパターンを理解すれば迷うことはないと思いますが
一度直接と間接のパターンを確認しておきましょう。