When you're reporting what people said in the past, you use past tense like this:

She said she was hungry, so we stopped and got some food.

In this situation, the person's words were probably "I'm hungry" but when reporting what she said, you change it to "she was hungry".

But what if someone said something about the future like this:

I'll send him an email later today with all of the details.

In that case, you report the speaker's words using "would":

He said he would send you an email later today.