Hi David,
you can just type in My Folder into the field. You don't have to enter 'Library1' at all.
If you'd like to display content from the folder's subfolders, just enable the 'Show subfolders content' property right under 'Path'.
Using 'My Folder/%' would display the contents of all the subfolders but not of 'My Folder' itself.
Hope this helps!