how to find specific area of a .PNG image?

hi friends,
i am new to unity, i have a .PNG image of flag and i have to fill it with different color …
please help me
jayant

wrong section to ask.

You should use a material and change its color instead of modifying the texture.

http://forum.unity3d.com/threads/154397-Team-color-shader-on-Asset-Store-released