First go to this link>> https://collaboration.skype.com/promotion/ to be a member of skype primium account.
in the email box enter your email address and then click send button.After that go to your email id which you have typed in the email address box.
then open the email named Skype.
Now copy the voucher code from the email and click on Redeem.The Redeem will take you to skype's website and there you have to log into your skype account.After login you will asked to type the Voucher code,then paste the Voucher code and click on Reddem.Thats it then you have to wait 15 minutes.Then your Skype account will be primium.
After making your account primium you will get a mail to your email address where you can see like this...