Can you put directing notes in your screenplay?

If you are the director as well as the writer, certainly. If not, the answer is less straightforward.

Directors can get annoyed with writers inserting too many directing notes in screenplays. Directing is their job, and those choices are theirs to make. Both in addition to and because of that, too many directing notes makes your screenplay feel unprofessional. They also can break up the flow.

Occasional directing notes can be okay if used sparingly. But remember that the director makes the final decision anyway.

There are ways to couch the same message in action or description without explicitly noting the director. In the links below, John August answers different forms of this question and provides various examples.