First you need to draw a christmas tree and cut it to make as a stencil.
Fold a paper in half and put it underneath your christmas tree stencil.Tape the top and the bottom of your paper so to make sure it doesn't move.
With your Q-tip,start painting.
Put some colorful dots for ornaments to look like a colorful christmas balls.
When done,take the stencil out and put the star sticker on top the tree
Now here's another way,try to put the dots for christmas balls first followed by the green paint for the tree.This is the effect
Here's a picture using sponge.(below)
Write "Merry Christmas " at the bottom or at the right side and you're done!