If when you open the game, it doesn't let you play. Go to the data folder (from the game you just downloaded) and open mugen.cfg with notepad. If you can't find mugen.cfg, press CTRL+F on the data folder and search mugen.cfg. After you have opened it with notepad, press CTRL+F in the notepad window and type height then press "Enter" key to search it and change the numbers next to it to 640 then look for width and change it to 480. Open the game and it should work.