Ok. I'm not very good with maths ;)
In your example you need to insert new object - keyboard.
Now that you have keyboard added. Create new event and select keyboard and key is down. Choose your key by entering the right arrow.
Now copy all the every tick stuff and drop it there.
To reverse it is a little tricky you got to do opposite of everything pretty much. like add becomes subtract.
I am not good with maths, so you going to have to play around with it.
Of course change the images to those of your menu options :)
Nice example - I presume it came with a tutorial - hopefully they explained the maths :)
EDIT: Wasn't too hard.
Here is capx Edited Capx