You should go to the special option at start of game. You'll then see options such as costume credits and cheat.
Enter this cheats there and enjoy the game ;)!
FUNKYTWN = Cartoon Spiderman
STICKMAN = Stickfigure Spiderman
CLUBNOIR = Ben Reilly Costume
ADMNTIUM = God Mode
UATUSEES = What If Challenge
RGSGLLRY = Character Viewer
CINEMA = View Movies
FANBOY = All Comics
MME WEB = Select Level
KIRBYFAN = PC Covers
ROBRTSON = Storyboard Viewer
SM LVIII = Quickchange Costume
MRWATSON = Peter Parker Costume
KICK ME = Amazing Bag Man Costume
XILRTRNS = Scarlet Spider Costume
SYNOPTIC = Spidey Unlimited Costume
TRISNTNL = Captain Universe Costume
MIGUELOH = Spidey 2099 Costume
SECRTWAR = Symbiotic Costume
RULUR J = James Jewett
EGOTRIP = Pulsating Head
GLANDS = Unlimited Webbing
LEANEST = Unlock All
WEAKNESS = Full Health