Dealing with cold and wet is a lot more than just equipment! Backpacking in serious cold and wet conditions requires serious experience and training. Car camping is a good place to start, test your equipment and gain experience while you can bail out to a warm car if things go bad. In fact, your back yard is a fine place to start! Day-hike snowshoe trips are also a good way to learn winter travel. Many National Parks have short Ranger-led winter snowshoe trips. Most ski areas also have cross-country trails. If you want to backpack in the winter first you must learn to be comfortable and have fun in the snow (or whatever winter conditions exist in your area). The next step is to camp overnight. Lots of other skills may also be needed- like avalanche safety.