WordPress.org

1. Upload the files to wp-content/plugins/nextgen-gallery

2. If you would like to use a Flash slideshow (only a option), go to Longtail Video, download the JW Image Rotator and unpack the conent. Upload the file imagerotator.swf to your WordPress Upload folder

3. Activate the plugin

4. Add a gallery and upload some images (the main gallery folder must have write permission)

5. Go to your post/page an enter the tag '[nggallery id=x]' or '[slideshow id=x]'. See more tags in the FAQ section

That's it ... Have fun