I am trying to make a wedding collage for my niece and I’m not sure what to put in for the size. I want the finished photo to be 16×20. I entered 43:57 (I know that is for 18×24 but…) when it came up on my screen it was a teeny tiny black rectangle. Do I need to enter my dimensions in another way. It would be nice if you could just pick your sizes rather than have to figure out these numbers to enter to hopefully end with a usable picture. Can you tell me how to have a blank canvas that I can drop pics onto that would end up being 16X20.