Set a passphrase for your Wallet, then save the wallet.dat - if you are on Windows that file is in your User home directory C:\Users\\AppData\Local\Bitcore.(I not sure, if it is in the Local dir or Roaming, but one of those)
If you ever reinstall your system, to recovery your wallet just replace the wallet.dat in your new installation.
HODL!
you can get a backup file easy by go to "File" => "Backup wallet..." and keep it in mail or dropbox, make sure it can't lose.
oke thank you . so BTX wallet didnt have private key such only word like BTC or ETH ?
No. You have to save a backup of the wallet every time you a new address (regular or change) to receive coins. The passphrase is only for unlocking your wallet to keep it more secure. If you do not keep a current copy of the wallet.dat file you won't have all the private keys for all the addresses you have used.