Sorry for the newbie question....

I want to create a collage NOT using one of the standard collage templates. (I want to use more images than in the templates.) Can I do this? Or can I add more images to one of the templates? I can't see how to add an image to a blank project or a collage template. Cut/paste and drag/drop don't seem to work, and I don't see an "Insert Image" command or icon. Am I missing something obvious?

Thanks in advance for any help.