i need to transfer my number and upgrade my plan

Habes

oready i do active new sim card withnew number but o need to transfer my old number to fizz and upgrade my plan to

Mike

Sorry but I did not understand what you want to do

To transfer you number you need a SIM

You want to use an old SIM associated with a plan and transfer the number to this one?
If this is the case you need to unsubscribe and after make the procedure to transfer your number to a new plan using the old SIM, since this is a new plan you can customize as you wish