I have a volumetric atlas in nifti format. I can open this atlas in freeview. Using the Lookup Table>FreesurferColorLUT, I can see how every label has a specific color. When I move the mouse cursor over an area of this atlas. I can see the name of that region (label). My question is how can I edit the name of the regions in that atlas. 

I am sorry if my question is basic. I couldn't figure out how to do it :( 

Thanks for any advice you may provide.

John