Picasa is an image organizing & photo sharing website. Picasa was originally created by a company named 'Lifescape'in 2002 & is owned by Google since 2004. Picasa web is now integrated into Google+ account. The Picasa software on your desktop now includes 'Google+ Auto Backup' feature. 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 upload photos from computer to Picasa web:
1. Go to https://picasaweb.google.com/ & sign in to your account.
2. Once you have signed into your account, click "Upload" button located at top of the window.
3. A pop-up window "Upload Photos and Videos" opens up.
4. You will see 2 options, "Create a new album" or "Add to an existing album".
5. Select any one of the above 2 options.
6. Click "Select photos from your computer".
7. "File upload" window opens up. Browse & select photos that you want to upload.
8. Click "Ok" or if you want upload more photos then click "Upload more" located at bottom right of the window.
9. You have another option to upload the photos i.e "Drag-and-drop". Here you can simply drag your photos directly from your computer to a location in your Picasa web account.
You can install PicBackMan's Picasa uploader for Mac from the website and start backing up photos and videos.