Hi Naga,
You need to create a HTML form with three text boxes for name, age and comments. The value in the NAME attribute of each of these form elements will become a variable name in the page you submit to the page to.
Following this, connect to your database, select your database and use the following SQL query.
INSERT INTO comments ('$name','$age','$comments')
I am concerned that you have no unique index on your table, but that is another issue.
Regards,
David