How do I make a circle 2 different colors

[Scott32676464xour]

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!

[Ton Frederiks]

You can try Divide (lower left icon) in the Pathfinder panel, ungroup the result.

[SJRiegel]

You can do this without cutting the shape. Make a gradient with the color stops on top of each other - set its angle to 90° -- adust the stop position(s) until the line is where you want it.