Questions and postings pertaining to the usage of ImageMagick regardless of the interface. This includes the command-line utilities, as well as the C and C++ APIs. Usage questions are like "How do I use ImageMagick to create drop shadows?".
In this case the 'overlay' is the larger image, so should be the destination image (whcih determines the final size of the results). The -geometry can be used to offset the other image which should be 'underlayed' using a 'DstOver' -compose method. Altrunativeally you can use -gravity center to center the image 'under' the destination 'overlay'.