You cannot become a goblin on Runescape.
The only way is using a glitch and then you will be banned.
A goblin is an NPC - a non-player character, controlled by the computer. Other real players appear as white dots on the minimap, while NPCs (both monsters and NPCs which you can't fight against - such as the Lumbridge Guide and other tutors) appear as yellow dots.
Chat with our AI personalities
get goblin mail (2) dye them blue and brown give them to the goblin general
get yellow and red dye, use them on each other, and use it on goblin mail
there is no imp village but there is goblin village.
Attack goblins or buy at grand exchange.
It is upstairs the tower in the goblin villlage, in a crate