How do I get a python program to do nothing?

You could use a pass statement:

if condition:
    pass

Python 2.x documentation

Python 3.x documentation

However I doubt you want to do this, unless you just need to put something in as a placeholder until you come back and write the actual code for the if statement.

If you have something like this:

if condition:        # condition in your case being `num2 == num5`
    pass
else:
    do_something()

You can in general change it to this:

if not condition:
    do_something()

But in this specific case you could (and should) do this:

if num2 != num5:        # != is the not-equal-to operator
    do_something()