How to add images to the gallery
There are three ways to add the images to the gallery in Extreme Thumbnail Generator. You can see all images that currently added to the gallery on the first step of gallery creation - Images.
Add individual images
To select individual images to be added to the gallery you can click the 
button (keyboard shortcut Ctrl + I, menu command Images - Add images -> Add individual images...). This button opens a standard dialog which lets you browse your computer to find the images you want.
Add all images from the selected folder
If you want to add all images from a selected folder automatically - click the 
button (keyboard shortcut Ctrl + F, menu command Images - Add images -> Add all images from folder...). You will see the dialog where you can browse your computer to find the folder you want. After the folder is selected and you click OK, the program will search the selected folder for images in all supported input formats and add them to the gallery.
Drag-and-drop images
Another way to add images is to drag-and-drop image files from Windows Explorer. You just have to drop them right into the image list. Please note, that you can drop both image files and folders. If you drop a folder, Extreme Thumbnail Generator will try to find all images in this folder and add them.