Best way to "slide" an array?

[DeCeaseD]

Okay so.. I'm trying to display a list of categories, I have these said categories listed in an array. Basically what I want from this is display 3 of the 6 categories in a vertical line, than as I press the left or right key, I would like to cycle through these categories. I have done this.. but it isn't the desired effect that I want. I want these categories to "slide" left and right when you scroll through them.. Basically say I have, "Test 1", "Test 2", "Test 3" and "Test 4", 1 through 3 are displayed, 2 being the selected category, I than press the left key, Test 2 would slide to where Test 1 is display, Test 3 sliding to where Test 2 is, and than Test 4 coming in from the side going to where Test 3 was, so on and so forth. Anyone mind giving me some tips on what would be the best way to do this.. ? I can't think of any way to do it..