You should be able to dye them, right click the item and select "Dye" to open the window. There you will see the different root shades, click on the color of the dyes you chose and you will see which you can apply to the item. Certain armor cannot be dyed, mostly the green highlighted dungeon gear, you can tell if an item can be dyed if the item's icon has a small circle in the upper right.
Edited, Sep 13th 2013 5:18pm by Krycis