What are 'Private Keys'? and where do i find them in my wallet? How do I know it is a private key?
Depends on your wallet.
A Bitcoin private key is a 256bit (32bytes) random number (there is a max limit, but lets don't go into the details).
Often, wallets export them as a WIF encoded base58check string which looks like
Sometimes, wallet use HD (look up BIP32 if you are interested).
Then the root private key starts with "xprv" and look like
Search after "export private key" or "dump wallet", etc.