how to redeem coupons on RedEnvelope

My officemate told me that she has a friend who always purchases things online. Her friend can really save a lot because she uses her discount coupons when she buys something. Would you believe that her friend could save up to 30% especially when she orders at RedEnvelop. After talking with my officemate I tried to google RedEnvelop and indeed I found a website on redenvelop coupons. On their page there were coupons being offered and still active. I want to try it but I don’t know how to redeem coupons on RedEnvelope.