Did you know there are many shapes available to you in Photoshop Elements? You can do more with them than just make photo mattes. One trick I like is to use parts of shapes to make waves. Here is one example. See the waves in this layout I made?
1. Start a new scrapbook page. Drag a paper onto your layout, or just fill it with a color. I'm using yellow paper from Jeanine's Poppies kit.
2. Zoom out quite far, so there is a lot of space around your document.
3. Select the cookie cutter tool.
4. In the tool settings bar, click the down arrow of the first drop down menu, the Custom Shape Picker. Click on the double arrow on the right side of that drop down menu and you will find many categories of shapes.
5. For this tutorial, I'm using the one that looks like an interstate highway sign, in the Signs category. Double click on a shape to select it.
6. Click somewhere around your document -- it doesn't matter where at this point -- and drag out the shape. Do not click the green check yet!
7. Before clicking on the green arrow, mouse over the edge near one of the corners until your cursor turns into a double arrow. Then, click and rotate the shape. Also click on the corner and side handles to stretch it until it looks the way you like. I rotated the shape about 90 degrees and stretched it so only the wave on one side appears on my page. I also made note of where I was placing the top edge, around 8 inches down the page, thinking of the rule of thirds. (Activate your rulers in the View menu.)
8. After you have rotated, stretched, and shifted your shape where you want it, click the green arrow. This will cut your paper. You now have a creative shape you made yourself!
9. To make layers, as I did in my layout, add more papers and repeat.
10. If you wanted all your layers to be the same size and shape, you could use this procedure on a colored layer which you then duplicate as many times as you need for however many papers you're using. Then clip (Control/Command-J) the paper to the shape layer.
Explore the other shapes and have fun creating your own designs!