The procedure of determining the wavelength of sodium light using the Newton's Ring experiment is as follows:

1. Select any radius to perform the calculation.
   

2. Click on both ends of the rings to measure their diameter, and observe the values as they appear in the table.
   

3. Measure the diameter up to the nth ring.
   

4. Calculate the wavelength using the formula: λ = (D²n+m - D²n) / 4mR
   

5. Click the Calculate button to determine the wavelength.
   
   

Note: The experiment should be performed in a carefully controlled environment to minimize any external disturbances and to obtain accurate results.