Perhaps I should leave this to the professionals!
1. Find cotton or natural fiber fabric or whatever you want to ruin.
2. Run it through the washer. For the first time in years I actually washed a load using hot water.
3. Soak the item for 10 to 15 minutes in the soda ash solution.
4. Squeeze item until slightly damp. Tie or twist or whatever you want to prepare it for the die.  The fabric I tied. The shirts j scrunched.  
5. Place on rack as shown. You can see I used items found in garage and cabinets.
6. Cover with ice.
7. Sprinkle the dye.
8. Wait.
I will report back later. Today I am ruining two old cotton shirts and a piece of clearance cotton fabric from Joanns. My ultimate goal is table covers for house concerts.