Add pagination in wordpress admin in my own customized plugin

Easy Steps :

$pagenum = isset( $_GET['pagenum'] ) ? absint( $_GET['pagenum'] ) : 1;

Find total numbers of records

$limit = 10; // number of rows in page
$offset = ( $pagenum - 1 ) * $limit;
$total = $wpdb->get_var( "SELECT COUNT(`id`) FROM {$wpdb->prefix}table_name" );
$num_of_pages = ceil( $total / $limit );

Give limit:

$entries = $wpdb->get_results( "SELECT * FROM {$wpdb->prefix}table_name LIMIT $offset, $limit" );

Add this code where you want pagination:

$page_links = paginate_links( array(
    'base' => add_query_arg( 'pagenum', '%#%' ),
    'format' => '',
    'prev_text' => __( '«', 'aag' ),
    'next_text' => __( '»', 'aag' ),
    'total' => $total,
    'current' => $pagenum
) );

if ( $page_links ) {
    echo '<div class="tablenav"><div class="tablenav-pages" style="margin: 1em 0">' . $page_links . '</div></div>';
}