I already filed my taxes But I forgot to add my sons w2 and A 1099 misc from the state of California Franchise tax board what do I do

Your son should file his own income tax return if he received a W-2 and Form 1099. Do not add those forms to your income tax return.

 

If you meant that you already filed a tax return for your son, then amend his return.

 

The W-2 and 1099 may change both federal and California so start the amendment process for both federal and state.

 

See How to Correct Federal Tax Returns and How do I amend my state tax return?