How do I make a circle 2 different colors

Hi,
im VERY new to illustrator and Adobe altogether, but I have been assigned a class project to create a personalized logo for our first Adobe project. My issue right now is making a logo that has 2 diffrent colors above and below the text in the middle. I would like the entire logo to be a circle with my initials in the middle. I above the letters I want it to be red and below I want it be to black but I can't seem to figure out the right way to cut the shape and make it happen. I'll attach some pictures to hopefully help with what I'm trying to do. THANK YOU!