I am glad you asked that question Bev, and I will make sure add a tutorial soon describing this subject, as a few may be sitting with the same question.
To crop an area of an image, you need to make a selection using the Selection tool found in the upper Panel (
third button seen on this image).
Make a selection by dragging from left to right and top to bottom. Once you release your mouse button you can move your selection around, so you can place it at the exact area you want to crop. Click the Crop button to crop the area you have selected (fourth button as seen in the image above).
I hope this will help you
