How do I add pagination links in WordPress?

/* Pagination */
// Numbered Pagination
if ( !function_exists( 'wpex_pagination' ) ) {
  function wpex_pagination() {
    $prev_arrow = is_rtl() ? 'Next <i class="fa fa-angle-right" aria-hidden="true"></i>
' : '<i class="fa fa-angle-left" aria-hidden="true"></i> Prev';
    $next_arrow = is_rtl() ? '<i class="fa fa-angle-left" aria-hidden="true"></i> Prev
' : 'Next <i class="fa fa-angle-right" aria-hidden="true"></i>
';
    global $wp_query;
    $total = $wp_query->max_num_pages;
    $big = 999999999; // need an unlikely integer
    if( $total > 1 ) {
      if( !$current_page = get_query_var('paged') )
        $current_page = 1;
        if( get_option('permalink_structure') ) {
          $format = 'page/%#%/';
        } else {
          $format = '&paged=%#%';
        }
    echo paginate_links(array(
      'base' => str_replace( $big, '%#%', esc_url( get_pagenum_link( $big ) ) ),
      'format' => $format,
      'current' => max( 1, get_query_var('paged') ),
      'total' => $total,
      'mid_size' => 3,
      'type' => 'list',
      'prev_text' => $prev_arrow,
      'next_text' => $next_arrow,
    ));
    }
  }
}