... I need help.. :(
....please teach me how to make formulas that can input in showInputDialog .. :(

As a private math tutor for grade school children, you design an application to teach multiplication tables. As a prototype for your design, you begin with the number two. One set of controls contains the multiplicand and the multiplier, while the other set of controls contains the product. The game should allow for ten possible matches. The pupils should be allowed three attempts to select the correct product for the corresponding multiplicand and multiplier. When their selection is correct, the background color of the product should change color and a message should display to congratulate the pupil. if a correct selection has not been made after three attempts, a message should display to indicate and error. You also have decided to provide the pupil with a quiz that can be selected from a menu. The quiz should ask at least five questions and have the capability of accepting answers. When the answer is incorrect, a message should display to notify the pupil. The pupil should be able to continue answering until he or she selects the correct response or be able to escape if he or she does not know the correct response.

hate to be thát guy and all, but sometimes it's needed for the message to get through

you don't put those formula as input, you put them as text in the JOptionPane box and you get the pupils answer as returned input. quite easy.
all you have to do, is cruise through the JOptionPane API, and you'll be finished in no time.
so far, you've done no effort what so ever, except for copy-pasting your assignment here. what did you expect? us to do it for you?