Open a new image 500x200. Fill it with the color or texture of your choice.

Select the path tool. Path rounded rectangle, draw your bar, then select mode 3d round.

Draw your bar any size you would like.

Select the options button.

Select file, select the file you would like the pattern to be.

Select options again and choose tile the texture.

You can also use the same texture for the bump of the bar. That gives it a textured pattern.

Now you can add shadow or other things if you want.

Here is the finished bar. To get the 3 bars just repeat the steps above making each bar shorter than the last.
The same effect can be used for buttons.

I hope this helps if anyone has any questions feel free to email me.