Click on a Blue letter, then click on a red letter in the list of unused letters to enter it in the solution.

To erase a letter click on that letter in the cryptogram.

To enter a letter position cursor at the appropriate point above the blue letters and type your choice. It will be entered at all places it occurs in the cryptogram and the cursor will advance to the next blank position. If you have already used that letter then the choice will not be accepted and the cursor will not advance.

To delete a letter click on the letter you want to erase and press delete

To move the cursor use tab and shift-tab