The red pencil points to the place, where you are to insert 
a letter or punctuation mark. Sometimes you are to choose the 
conjoint or separate spelling. All of that can be done using
the left mouse key or keyboard.
Notice that it may occur that no symbol is needed at all.

USING MOUSE.

Choose the right symbol in the lower left corner of the screen
and press the left mouse button.
You may refuse or confirm your choice pressing the buttons
"Cancel" or "Enter" with the help of mouse. (These buttons
appear also in the lower left corner of the screen.)
If you enter a wrong symbol, the needed rule appears on the screen,
and you can choose again. If you choose the wrong symbol TWICE,
the right symbol automatically appears in the needed place 
on the screen.
You can read the needed rule BEFORE your choise pressing the button
"Hint", but if you do it more than twice, you won't get any mark at
the end of the job.
After you  enter all the missed symbols on the screen, press the
"Next" button and go to the next screen.

USING KEYBOARD.

Enter the needed letters and punctuation marks using the
corresponding keys of the keyboard.
Press the "Del" key if no symbol is needed or in the case of
conjoint spelling, and the Spacebar in the case of separate
spelling.
You may refuse or confirm your choice with the help of keys
"Backspace" or "Enter".
Use the key "F2" to read the needed rule BEFORE entering a symbol.
After the task is over press "Enter" to go to the next screen.   