To select a piece of text, use the Shift key with the arrow keys. The options are listed in the main menu. For instance, to select a line, press Shift+down arrow.
Once selected, the text can be copied to the clipboard with Ctrl+Ins. The clipboard is exported immediately when the selection is copied and is available via the clipboard to other applications in the system.
To move a whole function, use the Copy function option from the Edit menu. This will copy the selected function to the clipboard. You can then delete it and place it somewhere else.
To insert text from the clipboard, use the Shift+Ins keys. To insert a file at the cursor's position, use the Insert file option from the File menu.