If you want to transfer your account and all your backed up data from your old Computer to your new one, follow these steps:
1) Find the original invitation email from your Inbox.
2) You can find the download link and your username from the email message
3) Download the client (PC or Mac version)
3) In Set-Up phase, you can fill in your usename and then click Forgot your password? link to obtain a new password via email.
4) Fill in your new password in the Password field and select your language; also accept the end user license agreement
5) It is recommended to restore the data from your old computer at this point. Click Restore and select the restoration options of your choice.