[Save Project]
After you finishing your creation, you can click menu "File" > "Save Project" to save this project. You can open this project to edit in future. The project file is *.dpf.

[Open Project]
Click menu "File" > "Open Project" to choose a *.dpf file to edit.

[Save Picture]
You can export your creation as a picture. Please click menu "File" > "Save Picture" or "Save" button save your collage.

[Save as wallpaper]
If you want to save your collage as wallpaper, please click menu "File" > "Set Wallpaper" to save it.