This is one of the templates in the Certificates section. Open it as a new document. Click on the fancy border to select it. It should get little x's in the corners. Arrange/Unlock. Cut.
Go to Preview. File/New From Clipboard. Save as a JPG.
Open the JPG in Photoshop (or Photoshop Elements). Enhance/Adjust Color/Color Variations. Choose to pump up/down red green and/or blue repeatedly until you are happy. Save as a JPG.
Drag the JPG file into the Pages document from wherever you saved it. Arrange/Send to Back. Position and resize it. Arrange/Lock
Note: I tried going straight into Photoshop Elements without the trip through Preview but I ended up with a low-res image. If you know how to retain the image quality without first going through Preview, then skip that step.
