am filling the payment method form now i do not know the security i should put and also the cvv

Then, that payment mode will not be acceptable. See Add funds to your Apple ID https://support.apple.com/en-us/HT208687

"Before you can add funds to your Apple ID, you must have a valid payment method on file. Learn about the payment methods that you can use with your Apple ID. ... See how to Add funds to your Apple ID https://support.apple.com/en-us/HT208687  Note that "after you authorize the payment, the funds ... [are credited] to your Apple ID. Then, you can use the credit to make purchases from the App Store or iTunes store. Need more help? Contact Apple support for help here: Get started."

You are very welcome. Be safe.

If you are trying to add a credit card, the security code/CVV is the 3 digit code on the card. See the link below.

https://www.cvvnumber.com