Upload photos to PicasaWeb: (From Picasa Website: http://picasa.google.com/support/bin/answer.py?hl=en&answer=39499 )
Sign in to Picasa Web Albums at http://picasaweb.google.com
Click the Upload button.
Now you need a destination album. Choose to create a new album or select an existing one. For new albums, adjust your settings:
Set your album title, date, privacy, and name tag visibility.
Share your photos with an existing Google contact group. You can also let those people contribute photos to your albums.
Select the photos you'd like to upload. What browser are you using?
Firefox, Chrome and Safari: You can upload a maximum of 5 photos at a time. Just click Browse and select your photos.
Internet Explorer: Upload any number of photos up to your Picasa Web Albums quota. The first time you use this option, click the Upload Control link on the right in the upload dialog. You'll need to install the Active X plug-in when prompted.
From the 'Upload Settings' drop-down box, select the size you'd like to upload.
Complete the upload.
You can also upload photos directly from iPhoto on your Mac. You'll need to download the Mac tools from the Picasa web site: http://picasa.google.com/mac_tools.html
To upload your photos from iPhoto, please follow these steps: (From Picasa Website: http://picasa.google.com/support/bin/answer.py?hl=en&answer=45158 )
Open iPhoto and select the photos you want to upload.
Choose File > Export. For some versions of iPhoto, you will need to select Share > Export.
In the Export Photos dialog box, click Picasa Web Albums. If prompted, sign in with your Picasa Web Albums username and password.
To upload to a new Picasa Web album, click New Album and enter a name and description. To upload to an existing album, clickExisting Album, and choose an album from the pop-up menu.
Click Export to upload your photos.