1996 Chevy Silverado if mine is fuel injected how do I carb

You probably don't want to hear this but you are far better off fixing the FI than going to a carb.

You would have to remove the intake manifold and replace with carb manifold, remove high pressure fuel pump and go to low pressure FP at around 5-6 psi vs 45-50 psi.

You would have no connections for MAP/MAF sensor, so check engine light would be on all the time.

Probably your best bet is to go to Summit racing or Jegs for a kit. Edelbrock makes conversion kits, I believe. Check with tech departments at Summit or Jegs for details.