Adding to DC (DC Universe Supplement)
From D&D Wiki
If you are inclined to add creatively to the DC Universe please feel free to do so. Lesser known heroes and villains or new and on-the-rise heroes and villains can be added. New organizations and cities are always welcome.
If you seek any assistance or have questions regarding the appropriateness of what you wish to add, just seek out User:Hooper, the DC Universe representative on the D&Dwiki and he'll gladly help out.
If you wish to try out some items or additions, use the DC Universe Sandbox.