The Picasa web album for photo publishing is generally given for free download as a software for every OS, but still if you choose not to download the software and directly upload the images through emails sent to the Picasa site, then here is something about it -

Go to your Picasa account.

Then go to the Settings page.

Then check the option - “Allow me to upload photos by email.” It would open up as given in the image -

The option will ask you for a secret word which will be included in the email address, and so the email address is not public but is unique only for your web album.

By default, the email address will be - username.secretkey@picasaweb.com
You can attach up to 20MB of photos in JPG, GIF and PNG formats, which is a pretty reasonable limitation.

When you get the email address, save the settings and then send an email to the email address given only for you, with the photos as attachment and Album name in the Subject field. Your photos would be published to the web directly.