need help to modify code in header

hello all,
i am running site https://www.jntuhub.in , here i need a help from u guys to place one ad in header.php . the problem is i need to display those ad in the main page only . and i need to hide when some one goes to some post. here is the example for such site https://www.jntunews . com.. here in main home page u will find header ad.. but not in posts…