1. Where can you get a public and private keys?
2. How do you unlock Bitcoin that are assigned to your public key?
3. What is The main difference between Public and private keys?
I'm asking this question because I was taking Wallet addresses to be same as My private key. Don't blame there are part of the reason you can call me Beginner in this space.
You can give people your bitcoin address which can be used to pay you bitcoin, but that is not private key. Do not give anyone your private key because it can be used to steal your coins. You can use the private key to recover your bitcoin wallet and spend the coins on the addresses the wallet generate.
Wallet these days are hierarchical deterministic (HD) wallets which generates seed phrase. The seed phrase can generate many child private keys, child public keys and their bitcoin addresses from bitcoin master private key. The child private key is what you are referring to. You may not see it on your wallet, but you can make use of Electrum if you want to see the privates key of each bitcoin address, or you can use
https://iancoleman.io/bip39/ to generate a wallet and go through what it generates for you to understand. Most wallet these days may not reveal the private key.
I am not implying that you should use
https://iancoleman.io/bip39/ to generate wallet for use but just to educate yourself.