1999 Toyota Corolla Add coolant to the car

Engine Cooling problem
1999 Toyota Corolla Two Wheel Drive Automatic

Hi,

I have a question about adding coolant to my car. I add green color Prestone coolant to both the radiator and the reservoir of my car, but I notice that the coolant inside is red color. My questions are
1. Will the green color coolant be OK together with the red coolant?
2. Should I add coolant to the radiator or the reservoir?
3. I splashed a little coolant out side when filling it into the reservoir, should I wash is off?

Thanks a lot!
-Jing