We probably need more information about how you expect your selection screen to work...
Have you got an example image you can post with a description about how it should work?
Most likely what you will need is simply a global variable that you can change based on the button clicks - the variable value can then be used to display the character you want to use - but without knowing more, that's about all I got.
~Sol
Just check my google plus page its Dimondman_ Modder you can find a picture of my problem