To flock an artificial Christmas tree, you will need flocking powder, which can be found at most craft stores. You can also use real snow, but it's not as long-lasting as the flocking powder. First, make sure your tree is clean and free of any dust or debris. Then, use a brush or a spray bottle to apply the flocking powder evenly to the branches. Once the flocking powder has been applied, you can use a hairdryer to help it set. Finally, you can add some decorations to your tree for a festive touch.