Hit the fx button near the equation bar, then chose IF:

a box will pop up with 3 input lines
first line is your main judement. Say something like X>2 (or whatever cell you want for X)
second line is if its true. If X = 3 or whatever, then put what happens when your equation is true.
second line is if its false. If X = 1, it'll put whatever you want the new cell to say if its false.