shipping price based on order total

I am trying to set up shipping where the greater the amount of your cart/order the less the shipping will be but I do not see an area that gives you the option to do so.

Order value up to $20: $5 Shipping
Order value $20 – $50: $3 Shipping
Order value over $50: Free Shipping

I saw on the woo theme site under woo commerce that there was a per order area, however in the plug in through wordpress this is not an option! Please help if anyone knows how to do this!!

http://wordpress.org/extend/plugins/woocommerce/