Load your MCEdit program, either by clicking its link in the Start Menu directory or by double-clicking the desktop shortcut if you have previously created one.
Expand the "File" menu, select the "Open" option, and navigate through your file browser to choose a "Minecraft" map file. Pick the file that you plan to play on when facing giants.
Expand the "Import" menu and scroll down the list to the "Spawners" option. Hover your cursor over the option until another menu appears beside the list, and select the monster spawner labeled "Giants." Monster spawners are the devices from which enemies materialize.
Click on the empty grid space where you want your giant spawner to be located. It will be easier to find if it is near your designated spawn spot, often in the middle of the map. Save the map file so that the giant spawner appears in your game.
Load the "Minecraft" program and choose the map that you edited. It will have the same name as its file name. Approach the giant spawner, within 16 grid spaces, and wait until a giant spawns."