Adding New Field to Add/Edit Post page

I have added a new text box on the page edit-form-advanced.php

Lets say i have created this text box for user to manually enter a date and i have also created a field in my posts table for this text box data.

Now How do i put the data of this text-box into a query and execute that, on click of publish or update post button.

I am new to word-press. Thanks in advance.