How do you save anything with Image Garden? It just wants to print.
According to the official manual, you have the possibility to save the images that have been fixed using the Save Selected Image function available withing the application. To find more information about it, access the online Canon page created especially for this purpose: http://ugp01.c-ij.com/ij/webmanual/MyImageGarden/M/2.0/EN/MIG/mig-304.html
From Canon support: