Is that a standing legendary? I think yes. You'll need to read my guide for standing legendaries, then. One section, green, is for DPPt, but the blue stuff is for HGSS. Read everything printed in black. I didn't write those guides for people who never hatched a shiny pokemon though, so you might want to try doing the breeding part first. I didn't explain everything in detail because I expected people to learn breeding first.