1, first open PICASA and then open the image to be watermarked in PICASA. Select the pictures (single or multiple) to be watermarked.
2. The menu bar-File-Export-Export dialog box appears. The dialog box has an input field for adding a watermark, in which you can enter the text content of the watermark. As shown in the figure below:
3. Click "OK" to start exporting pictures. All exported pictures will be watermarked.