To use coupon, you can use WP hotel Booking Coupon plugin.
You go to your Dashboard => Sailing => Plugins => install “WP Hotel Booking Coupon” plugin.
To use coupon, you go to your Dashboard => WP Hotel Booking => Settings => General tab => Check “Enable Coupon”.
Then you go to your Dashboard => WP Hotel Booking => Coupons => Edit/Add new coupon.
You can set discount type, discount value, validate from, vatlidate until, minimum spend, maximum spend, usage limit per coupon…in the coupon settings.
Finally, when you are at cart page, you can enter coupon name => Click “Apply Coupon” to use it.