Clicking this will display a browse window where you can choose the image files you want to include in the GIF animation. Just locate the files and click on them. If you want to choose more than one file from the directory hold down the control key while clicking on the file names. If you want to choose all the files in a directory click on the first file and hold the shift key and hit the end key this will select all the files. Once you have highlighted all the files in the current directory you want to convert click open. If you want to include files from more than one drive or directory you will need to click this more than once.