In indirect speech I have seen that said and told is used

where we have to use said and where we have to use told?

- 'Said' can be used when a person is saying something, also when a person is saying something to another person.
For example: She said that it was hot the previous day.
 She said to me that it was hot the previous day.
- 'Told' can be used when a person is saying something to another person.
For example: She told me that it was hot the previous day.
- For giving commands, 'told' is used.
For example: The teacher told me to close the door.
So, 'said' and 'told' are interchangeable in many cases in indirect speech, but not in all cases.