Transparent Box
A transparent box can look great on a simple layout. You can write a text over it or just simply use it as decoration. I will try to explain how to make a transparent box on this page.
Step 1: First make a layout or choose a picture you want to put a transparent box on. I have chosen this picture:
Step 2: Now use the
rectangle tool, which looks like this:

to make a rectangle on your picture in the size you want(you can edit the rectangle afterwards if you're not happy with it). You also can move the box around and put it where you want it.
Step 3: Click
Layers >> Properties. A new window will appear. Here you have to change the
opacity to 50%. It's up to you how you want the box! So if you want you can choose another opacity than me.
Step 4: When you have clicked on the "ok" button the transparent box is finished. Now you can apply some text to it or whatever you'd like! Here's how my picture turned out: