To create a confetti dyed piece you start by soaking the fabric in soda ash and water for about 30 minutes. Remember this step prepares the fabric for dyeing and accepting the dye in the most colorful way!
Next wring out the fabric and lay on any surface. I've used a table, the ground and even a bush! Sprinkle the dye powder across the surface.
Another option is to scrunch the fabric and allow more opportunity for the dye particles to separate and spread. Again, if you want more movement spray the fabric with soda ash and water.
How about moving the dye around with a found object... go for it and try weird things!
What do you think might happen if you were to fold your fabric before sprinkling the dye?
I encourage you to go have fun - you can't possibly make a mistake because there are no rules!
Let me know how your experiments go.