We are going to start this tutorial with a document of whatever size you need. After you have created the document, Use the Bucket Tool and fill it with the color of your choice. I am going to fill mine white.

Select a brush of an appropriate size and then go to the Brush settings. I chose a round brush size 7 and then I selected the following settings:

Then I select scattering.

And then i select the Color Dynamics.

Lets draw the confetti now. Select the color you see in my canvas in the corner of the picture and then start drawing your confetti. I drew strokes from left to right and then back and forth as if i was drawing a backward S.

Change the color in your palette and repeat.

Change the colors every time to get a multi color ressult.

In my case, this is the last color I am going to use.

And this is my final ressult.