With CoolCollage you can create amazing compositions of your photos and use them as a screen saver, desktop wallpaper (that changes automatically) or anything else like albums, prints etc.
Here is a quick start to get things going:
1st Step: Select folders with pictures
From the "Picture Folders" tab (click using mouse to select), using the add/remove buttons at the top-right, add folders with your pictures. Note that all sub folders are included automatically.
The folder list on the top shows folders used to select picture for the screen saver and desktop wallpaper. The bottom list shows folders used for collage generation.

2nd Step: Set options for desktop wallpaper
From the "Wallpaper Settings" tab you can choose to have the desktop wallpaper change on computer startup, or on a specific time every day, or have it change every x minutes (like every 60 minutes). Set these options here.

You can also click "Preview" to check out how the collage will look in a preview window, or click "Update Wallpaper" button to update the windows' wallpaper immediately.
You can find more information about the collage options here.
3d Step: Use as a screen saver
Set CoolCollage as the Window's screen saver from display options.

You can fine-tune settings that affect the screen saver from CoolCollage, under the "Screen Saver" tab.
4th Step: Generate Collages for creative purposes
You can create collages in any size from the "Generate Collages" tab.

After clicking the "Create Collages" button, you can view all the generated collages and choose your favorite to print, use in blogs or social networks or any other reason that you want to show off your pictures! See here for more information.