coupon only valid for $100 above purchase

[Girlysaffair 0]

HI, I have downloaded coupon code. But how do I configure to able only certain amt of purchase then it can be used? I was told "A very simple way to do this would be to only show the input box if the cart_total is greater than 150". But I am clueless on how to access which path to search to amend the cart total.

 

I need it for eg: $150 above your entitled to 40% discount

and $400 above entitled to 50% discount.

 

Please help. Thank you very much for your time.