Below the date, when you put the address of the person u are writing to, it goes like this:
John Doe, Esq.
In the salutation line, it goes like this:
Dear John Doe:
If you do not know if the hiring person is a lawyer (some public agencies are like this), then include their name but no Esq., (obviously).
One side note, never never never never use "To Whom It May Concern". Your cover letter, resume, etc. will be thrown out. Do whatever you can to find out the name of the person doing the hiring. Call them, check NALP directory, anything, but never use that phrase.