WordPress.org

The plugin is simple to install:

1. Download the zip file
2. Unpack the zip. You should have a directory called altpwa, containing several files and folders
3. Upload the altpwa directory to the wp-content/plugins directory on your WordPress installation. It is important you retain the altpwa directory structure
4. Activate plugin

To use it just to that. If you want to have a page to list and show all your albums from Picasa Web Albums, wrote in a blank page

[altpwa user=...]

and instead of ... indicate your Google username from Picasa Web Albums.

If you want to show only one album, in a post for example, wrote in a blank post

[altpwa user=... album=...]

where of course the ... are replaced with your username and the album. For example, I have an album like that

http://picasaweb.google.com/foto.capan/BratislavaZiuaI

Than to embed it on a post I will use

[altpwa user=foto.capan album=BratislavaZiuaI]

That's all!

See the configuration page of the plugin where are several useful options.