somethins wrong with my games screens PLZ HELP

whenever i go to play Combat Arms or Stepmania,the game screen is too small.i dont know how to maximizethe screeneither.Also i feel like downloading maplestory again but i feel like the screen will be small on that too.does anyone know how i can fix this?

Increasing the game's/screen's resolution maybe?ArchDuke1

the game is already set at fullscreen though