About the goblin mail, its easy. You gotta make dye, aggie the witch in draynor village will help you with that, but you wil need ingredients to let her make dye. Ill show the dye table:
Blue dye: 2 Woad leaves + 5 coins (for woad leaves, talk with the gardener in falador park)
Red dye: 3 redberries ( found just out of the edge of varrock) + 5 coins
Yellow dye: 2 onions (found in lumbridge near fred the farmer) + 5 coins
Orange dye: Mix red and yellow by using it on eachother (you'll need this for the orange goblin mail, just use the orange dye on a normal goblin mail)
Green dye: Mix blue and yellow dyes
Purple dye: Mix red and blue dye
Also, with the dyes you can change the color of your cape. Hope this help :happy