Picasa is a digital photo & video organizer which allows you to organize, share and edit photos on your Mac. Picasa scans your hard disk, gathers your photos & videos and sort out them into a folder. Picasa also allows you to import photos from external devices. You can use your Google account and backup photos to Picasa Web Albums. Picasa features basic editing tools. You can cut, crop, rotate & apply various filters to your photos. By using Picasa, you can adjust brightness, color and contrast as well. You can also create collages, photo CD's and slideshows with your photos. Picasa has some additional features like showing duplicates, sorting out by color and much more.

Here are the steps to Import Photos from iPhoto to Picasa:

1. Go to https://picasaweb.google.com/ & sign in to your account. If you don't have an account, then create one.
2. Download & install "Picasa Desktop Application" on your Mac & launch it.
3. Open Picasa Desktop Application & click "Import" button.
4. Click 'Import from' to select the source of your photos.
5. Choose the location to save the photos on your computer. If you choose 'date taken' option as a folder title, then your photos will be saved in separate folder by date.
6. Picasa offers 3 ways to select multiple photos.
   a) Rubber band select: Just click and drag your mouse over multiple photos to select them.
   b) Command key (Mac) to select multiple photos.
   c) Click the clock icon (Picasa select photos by time) to select all photos taken during a specific time period.

7. Select any ('a' or 'b' or 'c') one of the options listed above.
8. Select the photos which you want to import to Picasa.
9. Click "Import Selected" or "Import All" to import all the photos.

You can install PicBackMan's Picasa uploader for Mac from the website and start backing up photos and videos.