This tutorial will show you how to make waves like this one:

Open your sign or a blank canvas. I am going to be using a blank canvas.
First what you are going to want to do it make a new layer by pressing ctrl + shift + n
Get your marquee tool. On that new layer, make a horizontal selection and fill it in with a color. Mine looks like this:

Now duplicate your layer with the pink line on it and move it directly below the original pink line. Right click on the layer and go to blending options -> color overlay -> and select another color. Now mine looks like this:

Repeat. Now mine looks like this:

Merge all of your layers of the wave together.
Now go to filter --> distort --> wave and match your settings to mine

Press OK and then you're done! Here is my finished product:
