When you want to report what someone said you can either do it by repeating their exact same words, which is called direct speech, or you can use reported speech. When we use reported speech, the main verb of the sentence is usually past (Someone said that.../ I told her...). The rest of the sentence is usually past too. In general, the present form of the verb in direct speech changes to the past form in reported speech. For example: your friend said: "I want to buy a car." When using reported speech, we say: My friend said he/she wanted to buy a car.