If you are affiliated with a Performance Rights Organization (PRO) then they will have assigned you an IPI or CAE number. Your IPI or CAE number can always be found on your PRO's website. Most PROs have searchable public databases (sometimes referred to as a public repertory/repertoire) where you can find songwriter and publisher information, including IPI/CAE numbers and works registrations.
If your PRO does not have a public database, then please log into your songwriter portal with your PRO and look for your IPI/CAE number there.
If you're having trouble finding your PROs website, you can find link to their website here. If you're still unable to locate your IPI/CAE number, please contact your PRO for assistance.