I drive an eighty-eight olds mobile and in the winter it wont start and its not the battery because i bought a new one. can you tell me how to fix it

It still can be the battery as there are minimum requirements for the electrical system. They have a minimum Cold Cranking Amps (CCA) that can be found when you purchase a battery there is a chart for the vehicle make/model/year and minimum CCA requirement. If your battery doesn't have enough it will be difficult or fail to start. Also make sure that the battery undergoes a draw test before you buy a new one to ensure it isn't faulty. They'll attach clamps, like on jumper cables, to the battery that are attached to a box and meter. There is a button they press that draws a load from the battery and the meter will show that the battery can take the draw of starting an engine without a problem. Good luck to you