To define a new function, use the cursor to move to an undefined function. Press or to move the cursor to the entry line.
Type the expression.
Press when you are finished.

To edit a function, go to the Y=Editor, and use the cursor to highlight the function. Press or to move the cursor to the entry line. Use the left or right cursor to move within the expression to edit. Press when finished. You can press once or twice to clear an expression to type a new one.

 

To set the format for the graph screen, press and select 9.
Make your selection.