Wanda,
In order to copy & paste, you will first need to highlight the section you want to copy. To highlight, all you do is click the left botton of your mouse and drag it down over the area you want copied.
To copy, take what you've highlighted and press the "Control" key, and then while keeping the Control key pressed down, then press the "C" key. This means you have copied it to the clipboard (which you probably can't see) and so now you are ready to paste it. Go to where you want to paste it, and press the "Control" key again, and then while keeping it pressed down, press the "V" key. This will paste your document.
Another way to do it is, after you've highlighed the doc, right click your mouse key & press the copy function. Then go to where you want to paste it, right click again and press the paste function.
Softwares usually have shortcut keys at the top of the tool bar as well.

