Due to some security restrictions in most web-browsers, copying and pasting can't be done automatically. However, you can copy and paste in PERRLA Online by using keyboard shortcuts.
If you're using Windows
First, highlight the text prior to copying.
Now, use the Ctrl+C keyboard shortcut to copy. To use this shortcut, press and hold CTRL and then while holding it, press C on your keyboard.
Once you have the cursor where you want the text to be pasted, press Ctrl+V on your keyboard at the same time to paste your copied text. You can use this same paste shortcut for text you copied from anywhere on your computer.
If you're using Mac
Just like above, highlight the text you want to copy.
Use the keyboard shortcut Cmd+C to copy the highlighted text. FYI: Cmd is the Command or four-leafed clover key beside the spacebar.
When you're ready to paste, click where you want your text to go in the editor. Press Cmd+V together to paste the copied text. You can also use this same shortcut for text you copied from outside of PERRLA as well (just don't plagiarize).