Simple Question About Mouse Macros

Hey all,

Brand new to the programming of mouse macros, and I'm stumped by what may be the easiest task for you guys, so here I am. I simply want one mouse button, we will call it M3, to have 2 separate keyboard functions, and switch between the two. For example, I'll use keys F1 and F2.

I need to press M3, and it functionally presses F1 on the keyboard.
Now, I need to be able to press M3 again, and it functionally presses F2.
And repeat. M3 now needs to press F1 again, and then F2, and so on.

Thanks for your time reading a noob's question.