How do i change the color of my name?

you need a spray paint, which costs buttons (5, to be exact). you can earn buttons by either reviewing a cursor set, or playing cosmic journey: http://www.rw-designer.com/cosmic-journey

just a warning, spray paints are random! (which sucks) so don't be mad you didn't get the color you wanted!

view your workshope here: http://www.rw-designer.com/workshop

Appreciate the information bro thanks 😊
Can you also tell me which colors are available, so i know what I'm looking for?

Red, Orange, Goldenrod, Green, Purple, Coral, Pink, Gray, Black, & Navy (Not sold by Scunkie, only available through Mystery Presents)

source: http://www.rw-designer.com/spray-paints

I think sometime in the future it would be nice to have the choice of colour for spray paints and spray paint dispensers.

agreed

Why some colors are unobtainable??

First, you need to go to Cosmic Journey.