The metadata interface guide goes into detail about the structure of workspace metadata, but this page is for quickly getting a working metadata file together if you've downloaded a VM and don't have one.
This does not apply if you are using the cloud client obviously.
1. Download the template
Download this example metadata file. Rename it if you want to.
2. Change the name
Search the file for the instance of "http://example1/localhost/image" and change this to a meaningful name. This can be any URI, the name has nothing to do with file locations (as far as the workspace service is concerned at least).
3. Change the location URL to match the file
Search the document for "file://ttylinux-xen" and change this to match the filename. If staging to the site for use with propagation, use the appropriate protocol, host, and directory path.
Note: this quickstart does not cover multiple partitions or HD images yet.
4. Change the mountpoint
Search the document for "sda1" and change this to match the partition of the root filesystem.
The necessary value for this can be determined by examining the "/etc/fstab" file inside the VM (this quickstart assumes you are using a Linux VM).
(It is possible to mount the VM's filesystem locally for inspection and editing, for instructions see this offline editing guide).
5. Make sure the networking is set up
The template metadata file expects that the VM is set up to DHCP when it boots. Verify that this is true, this is often (but not always) the case for VMs downloaded from online 'marketplaces'.
The specific file(s) to inspect/edit varies among Linux distributions -- when faced with a distribution unfamilar to you, you can often figure out the proper configuration by running "grep -Ri dhcp etc" ("/etc" if inside the VM or chrooted). Or simply see the distribution's networking documentation.