To choose a creature type, you must choose an existing creature type, such as Halfling or Scout. You can't choose multiple creature types, such as "Halfling Scout." Card types such as artifacts can't be chosen, nor can subtypes that aren't creature types, such as Forest, Equipment, or Food.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.