What colors are normal for a period? it goes from bright red to brownish, then black. is something wrong?

Nothing is wrong: The color of the menstrual flow can change from day to day and include all of the ones you describe. If bleeding is somewhat heavy and the blood comes out quickly it can be bright red. Depending on how fast the hemoglobin loses oxygen and how much of a chance the vaginal bacteria have a chance to "eat" the hemoglobin, the color can become darker.