Welcome to Android Central! If you upload the photos to your Google+ Photos, that is essentially the same as Picasa on the web. If you want the photos locally stored on your computer for the Picasa computer program, then connect the tablet via USB and use the computer's file browser to drag and drop the photos to the computer's hard drive (into the appropriate Pictures directory). The Picasa program should then add them to its library (and also give you the opportunity to upload them to your Google+ Photos in the cloud).