For the chief musician

"This is for the director of music to use in worship"

set to Al Tashheth

This probably tells what musical style or tune to use when singing the psalm.

Possible meanings are 1) David wrote the psalm or 2) the psalm is about David or 3) the psalm is in the style of David's psalms.

The meaning of the word "michtam" is uncertain. You may use the word "psalm" instead.

"put me in a safe place"

"attack me"