Cropping
Sometimes you make an image bigger than necessary. Then it is smart to know how to crop. I crop my images all the time!
Step 1: Make an image or whatever. I will use this one:
Step 2: Select the
crop tool, which looks like this:
Step 3: Mark the aera of the image you want to keep! The dark aeras will be removed.
Step 4: When you are happy with how it will turn out, click on the little v-symbol on the upper tool line, which looks like this:

or press enter. Here's my finished result: