How to guess whether a noun is masculine or feminine?
There's no real secret to a noun's gender, but there are some clues:
About 80% of the time, if it ends in "e" it's feminine, and if it doesn't, it's masculine.
All words ending in "-ion" and "-ité" are feminine.
Of course, if you're refering to people, the gender of the noun will normally match the person's gender: le frère, la mère etc., but always le bébé (the baby), regardless of the baby's gender, and un enfant (a child), une enfante is very rare. You just have to learn the noun's gender at the same time you learn the noun!