upgrading from starry night pro plus 6.4.3 to starry night pro plus 7

       Hi.I own starry night pro plus 6.4.3 with User Name: Mark J.  and Registration Number: lu6-XXXX-XXXX-XXXX-XXXX.Because i own an earlier version of Starry Night,i can upgrade for a discount.I want the starry night pro plus 7 download only version not the box+download version.Pls guide me step-by-step(detailly) what i have to do in order to receive the download link in my e-mail including the updates and the serial number and how i install the starry night pro plus 7 in my pc,pls describe to me all the procedures i have to follow in order to receive the download link in my e-mail including the updates and the serial number and how i install the starry night pro plus 7 in my pc,as well as how i receive the username and the registration number(you will send me that to my e-mail?) and how i unlock these software.In other words,describe to me everything i have to know in order a succesful install of this software in my pc.Thank you