So many questions can be answered by simply right clicking in Lightroom. If you want to do something to anything in Lightroom, try right clicking it and see what you get. This is just a short list of things that the right click can do and by no means exhaustive. Just right click everything in Lightroom, even the little triangles at the edge of the screen, or the individual section headings on the left and right panels. Spend 20 minutes just right clicking. It will answer so many questions that you will no longer have to ask me about. As much as I like being needed… I’d rather have you exploring and discovering things for yourself.
And if you are on a mac, you do have a right click, you just need a mouse with a right click button. Or hold down the control key and click. (This is the point at which all PC users may laugh at the mac users. Your one chance!)