Replacing a battery is probably one of the most easiest things you will do to your car. If your battery is cracking at the top it is a sign that it needs replaced. Also on your dash display there is an icon that lights up telling you it needs replaced. Now you need to choose the battery you want for your car. Your best bet would be to call the dealer or an auto part store and get the battery that is made for your car. That way you are sure to get the right size. You always need a battery that is suitable for the weather your car drives in.
Make sure your car is turned off and the keys are out of the ignition. Pop the hood. Some batteries have a bracket on the top of them to hold them in place. Keep them attached until you have taken off the cables. Now with a ratchet, loosen the bolt on the negative battery cable. Twist and pull the end of the cable off the battery terminal. Remove the positive cable the same way.
Remove the bracket. If it doesn't have a top bracket it most likely has an adjuster on both sides of the battery. Loosen the adjusters so the battery can be freed from the battery tray. Take the battery out and clean the area for the new one. Use a wire brush to remove any corrosion. Make sure you also clean the battery connectors with the wire brush.
Now place the new battery in the battery tray. Tighten the brackets to insure it is securely in place. Now connect the negative cable back to the terminal, and then the positive cable. Be sure that the cables cannot move at all.