SQL Query Search page

you can use WP_Query(); to query the results.

it has an argument 's' => $search_query,

create an input, get the input value, store it in $search_query, then create a query,

$query = new WP_Query( array( 'post_type' => 'post', 's' => $search_query ) );
if ( $query->have_posts() ) : 
     while ( $query->have_posts() ) : $query->the_post();

     // do something...

     endwhile;
     wp_reset_postdata();
endif;