I see many people asking about opening their third eye. The answer is usually to "open the sixth chakra". However, the 6th chakra is NOT the third eye, rather, the third eye is an extension of this chakra.
The 6th chakra is actually located in the middle of your head. The meditations on this chakra should not really be employed alone, but as part of a whole chakra programme. The colour for this chackra is a bluey-violet. If you want to work on your chakras, you should work every day as the work is progeressive, and will deteriorate without practice. "Ohm" is the traditional chant for this chakra.
I would not recommend focusing on any chakra exclusively, and pushing your "third eye" to open without correct preparation is inadvisable. Rather, employ balanced chakra work with additional health skills, and nature will take it's course.