To choose a letter, move the cursor over it and pause. If you keep moving across a letter and on to another, it will not be chosen. When a letter is chosen it is added to the 'Message Area' at the top.
Choosing 'Faster' or 'Slower' near the top of the window will alter how long you need to pause before a selection will happen.
To choose a letter twice in a row (such as the two T's in letter) choose 'T' once and then move OFF the 'T' and back ONTO it.
Deletion of the last letter is done with 'Del'. 'DelWord' at the top will delete the previous word. 'Clear' will clear the entire message area. If you remain on the 'Del' or 'DelWord' the deletion will be repeated.
If you choose 'Cmd' at the bottom right another window will pop up with many commands to choose. One of them is 'Quit' - to exit Sue Center. Another is 'Help' - for complete documentation on all aspects of Sue Center. In these help pages the sequence Cmd > Quit means to choose 'Cmd' and then choose 'Quit'.
To the left of the letter area is the 'Word List' and the 'Short Words'. Read about both of these in the 'Word List' help topic.
If you choose 'Suspend' at the bottom it will change to 'Resume'. At this point the entire main window will be suspended and will be inactive until you choose 'Resume' to activate it again. This is used for when you wish to rest and ponder without choosing anything inadvertently.
Normally letters are entered in UPPER case. You can choose the 'SHIFT' command at the right hand side to toggle to 'Shift' or mixed case. The first letter after this choice will be in Upper case and the rest will be in lower case. Choose it again to enter a capital letter. Choose it twice in a row to return to UPPER case. This behavior may seem odd but it works well.