Now that we can enter new text, replace existing characters, delete characters and re-insert deleted characters, it would be nice to complete our capabilities by inserting new characters.
Move to the word "light" in line 4 and position the cursor under the "l". Change this word to "dark" by pressing the Del key 5 times, pressing Ins (i+), typing the word "dark" and then pressing the Ins key again to disable insert mode (i-).