In Pokemon diamond what do you do after you defeat Cyrus at the galactic veilstone building?

You have to save the legerdary Pokemon (if you're there you should know what I'm talking about) so head up there by using a warp panel, there should be one close by. Once you get there, beat Saturn (he has Kadabra Lv 36, Bronzor Lv 38 and Toxicroak Lv 40)and he will tell you how to release the Pokemon (push the red button)after your done go to spear pillar to get Dialga! ;)

Trust me I have the walktrough (you could've just seached on google for a walktrough!)