Use your discretion and adjust the function as you need it. It should make sense when you read the function. It currently sets a shipping fee based on the total cost of the cart.
// ADD SHIPPING COST function woo_add_cart_fee() { if (WC()->cart->cart_contents_total > 1000) { WC()->cart->add_fee( __('Shipping', 'woocommerce'), 100 ); }else{ WC()->cart->add_fee( __('Shipping', 'woocommerce'), 100 ); } } add_action( 'woocommerce_cart_calculate_fees', 'woo_add_cart_fee' );