I have black hair starting to see a few gray hairs. I would like to dye it a dark to medium brown. How do I do this, can I do it myself?

Dark hair has a lot of red pigment in it, so if you apply a permanent color on your hair, it will result in a red/orange shade. It would be best to get your hair done professionally. If you don't want to go to the salon, use an ash color. Ash base colors are great for dark hair, it helps to neutralize red tones in hair.