Sounds like you just need to put both segments of code in the same if statement:
No. That will just turn the LEDs on and off one after the other each time i equals 1.
Follow the advice given by jrdoner. You have all the programming elements needed to make it work in your code snippet. If you are unhappy with a boolean variable then declare toggle as an int and set it to 1. You know how to test if toggle equals 1.
If toggle equals 1 then turn on the green LED when i equals 1, then set toggle to 0.
If toggle equals 0 then turn on the red LED when i equals 1, then set toggle to 1.