Man, it's really not a beginner game type.
You'll need to learn about arrays, matrix. Then, you'll need to map your canvas with many small dots, the smaller precision, bigger your array.
For example, if you want draw in large pixels, you can div a canvas of 320x240 by 32 slots in the horizontal by 24 in the vertical, so, each slot will have 10x10 pixels of size, so, you'll check if the mouse or touch is over what slot and if clicked or touched, set it's slot with a created object of 10x10 pixels of size.
You'll be able to improve it by changing colors, using the effects, etc.
The sparkling is easy, just setup a particle to follow the mouse/touch and change it's configuration every time the mouse is clicked, for example, the number of particles shot when clicked, and after, returning it's configuration to the standard.
Well, I think you'll need more things, but it's the basic.