When publishing Layered Images, you need a Connector Configuration that defines the location where you will publish the images, preferably near the servers you intend to provision with the images. You can create as many Connection Configurations as you need.
Citrix recommends publishing Layered Images to the environment where the App Layering appliance is installed; in this case, XenServer. To do this, you need a XenServer Connector Configuration to define the publishing location. If you don't yet have a XenServer Connector Configuration, you can create one while in the process of publishing Layered Images.
See Connector essentials for more information.
If you decide to publish Layered Images on a hypervisor other than the one where the appliance is installed, you can publish to the appliance's file share using the NFS Connector. After publishing the image, you can manually copy the file to the desired location.