Picasa is a photo organizing & photo sharing website. Picasa is a good place to backup photos & videos. It is easy to use and is accessible from anywhere in the world. If you have a Google account, you can directly access Picasa web. Picasa allows you to store large photos for upto 1GB. Storage limit for 2048x2048 pixel photos or smaller (800x800 pixel photos) is unlimited.
Here are the steps to download a photo from Picasa Web to computer:
1. Go to https://picasaweb.google.com/ & sign in to your account.
2. Once you have signed into your account, click your photo from an album (which you want to download).
3. You will see a photo in bigger size.
4. Click "Actions" button located at top of the photo.
5. Select "Download photo" option.
6. Your browser prompts you to save .zip file, then click "Save" and specify a location to download. The downloaded zip file will contain the photo from the Picasa web.
You can install PicBackMan's Picasa uploader for Mac from the website and start backing up photos and videos.