There are two types of hair color; semi-permanent and permanent. Permanent color stays in the hair until it grows out, while semi-permanent color slowly washes out. Many people do home semi-permanent treatments, including henna. It is generally not advisable to do permanent color on your own at home. Color treatments are chemical treatments and they can be damaging to both hair and scalp.
Many people get contact dermatitis on the scalp from coloring. This is an irritation on the scalp than may cause bumps and inflammation. Coloring can also lead to hair loss and hair burning. Some people even have allergic reactions to coloring. It is best to leave this job to the professionals for sure.
If you do decide to color, be sure to use a good gentle moisturizer afterwards. It is also best to have the hair trimmed after, instead of before, the treatment. Special care needs to be taken with color treated hair to keep it from breaking and being too dry afterward.