Merry Christmas tree design

For the beginning create a new file (File>New) of 1280x1024 px and 72 dpi. Select the Paint Bucket Tool (G) and paint the primary layer the way it's demonstrated below:
Take now the Rectangle Tool (U) and stretch out the figure on the whole canvas. Set the next demonstrated parameters, making a mouse click on this layer on the layers' palette

Create one more layer, giving it the Opacity of 0%.

Give next indicated parameters for the made layer:

Now it's time to represent a rounded element, applying the Ellipse Tool (U), giving it also the Opacity of 0%.

Follow the shown parameters:

It's the result you must get on this stage:

Select now the Brush Tool (B) and try to represent the contours of a fir tree, like on the next picture:

Select out of the Custom Shape Tool (U) the same star indicated below:

Fill the whole fir tree's inside space with selected stars, changing also their sizes (Ctrl+T)

One star should be situated on the fir tree's top, giving it the next parameters:

This is the image you should get now:

Next we'll select three types of snowflakes, like those from below:

Placing the snowflakes in an arbitrary way on our picture, we may change their Opacity parameter on the layers' palette: Fill: 10%, 20%, 40%.

Choose out of the already known table a kind of figure like the next one:

Place it under the layer containing the top star, the same way situated below: Fill 0% on this layer:

Next we should select the next demonstrated parameters: This is the next stage of the picture:

Take now the Pen Tool (P) and represent several fillets on the fir tree, choosing the next colors' codes:

The final result!