Put your DVD in the drive and follow the instructions
I do not have the DVD or a DVD drive on my new computer
The important question is "Is this Premiere Elements 11 Mac or Windows?" If Mac, did you purchase it as the Adobe Premiere Elements 11 Editor from the Mac App Store?
If it is Premiere Elements 11 Windows or Premiere Elements 11 Mac from Adobe, then you can download installation files at this late date from the following web site and then insert your purchased serial number during installation.
If you do decide to go this route, make sure that you read Note: Very Important Instructions on that web site page, otherwise you will run into an Access Denied message.