First of all, you need to mark a region of text in the current buffer which you want to transfer into the kill ring. There are two ways that you can do this:
The selected text is highlighted using a bold font.
To mark the region with the keyboard, place the cursor at the beginning of the text you want to mark, press Ctrl+Space , and move the cursor to the end of the region you want to mark, using keyboard commands to do so . Unlike marking with the mouse, this does not highlight the region.
Because the editor does not highlight the marked region when you use keyboard commands, a useful command to remember is Ctrl+X Ctrl+X . Pressing this exchanges the current cursor position with the start of the marked region, highlighting the region in the process. Press Ctrl+X Ctrl+X a second time to return the cursor to its original position, but leave the region marked.
Press Ctrl+G to turn off the highlighting in a region.