private key – Why storing bitcoin in paper wallet is complex for me?

I created a paper Bitcoin wallet by using

So, I have the private key and public key.

I want to buy some bitcoin with my credit card and send it to my paper wallet by using the public key.

So, I am searching a website for this purpose. Only should I do is giving my public address, amount of money to buying bitcoin and my credit card infos.

However, the sites that I found, wants some ID, registration, their own wallets etc.

How can I find simplest site for this purpose?