Using these cards is super easy. Just take one out of the set, write your warm holiday wishes on the blank note card, and put it in the festive mailing envelope. Then, send it to your loved ones. When you open the greeting card, the mini pop - up Christmas Tree will add a lovely surprise. As for maintenance, keep the cards in a dry and cool place to prevent the paper from getting damaged. Avoid bending or folding the pop - up tree too roughly to keep its shape intact. And if you're not using all the cards at once, you can store them back in the set for future use.