Hello Ehadley! Geraniums of the outdoor border kind do not need overwintering. As the species has had some name changes, I believe you mean the pelargoniums, generally used for pots and bedding. Cut them down about 6-8 inches to a leaf, then bring them indoors into a cool, light, frost-free environment. Water sparingly, and put out again when there is no danger of frost. I have mine by my back patio door, where they get the light, but the temperature stays around 10C. If you have a cool windowsill in a spare room, this would also be okay. If they get too warm they could get leggy and weak.