Question

I want to add dummy pages (like typography) into the database “wp_post” table which contain textual information about the theme when someone install and activate my theme.

Answer 1

There are hooks which you can call to insert pages.

1- after_switch_theme hook is called when you switch theme (available if your wp version > 3.3.0 ) hook reference

2- wp_insert_post is used to create pages/post (more documentation at wp_insert_post)

Below code will be in your theme functions.php

<?php
function myactivationfunction($oldname, $oldtheme=false) {

}
add_action("after_switch_theme", "myactivationfunction", 10 ,  2);

Reference : here explained in more details regarding activation and deactivation of theme