If you are using a kit where the embellishment pieces are delivered all on one page, here are some simple steps for using these on your layout if you are not using Photoshop or Elements:
Open the png embellishment file.
Duplicate the file so that you are not altering the original.
Use your Cutting Tool, Cropping Tool or Eraser tool to remove the parts of the image that you are not planning to use on your scrapbook page.
Insert the remaining embellishment onto your page.