The XML file stores your settings (partition you image, drive to where you image, etc.). Go to Documents > Reflect where it is stored. If you double click on the file(s) in the folder, you'll see your definitions
Btw: if you ever want to delete a particular setting, do it in this folder.
If you make another definition (e.g. for imaging another partition or to another drive), you will get another additional XML file. All you need to do then is click on XML file and then highlight the file that you want to run. Then click on the cog wheel and off you go.
I usually have a few definitions depending whether I want to image my system partition only, my data partition only, both together, etc. You can have as many as you want. And you can name them in the very last little window of the definition wizard. Then they are easier to tell apart.