You must create and configure an image before you can start assigning desktops.
Creating an image is a two-step process.
First, install and configure agents on the desktop template provided by VMware, and copy the template into the file share.
Then, convert the template to a new image in the Administration Console. See Create an Image in the Administration Console. This image is used as the OS on your virtual desktops.
Once you have an image, you can start creating desktop assignments. See Create a Dedicated or Floating Desktop Assignment.