I also forgot to ask. What does the backup wallet do? Is this like a "system restore" feature in Windows that whenever you need to uninstall and reinstall the bitcore wallet, you'd still be able to keep your bitcores? Thanks in advance
you can export and save your private key. if something happens with your hdd you can import your private key and u have your btx back.
where can i find my provate key? i only can do a backup on file .dat ..
what he asked. same question...

To export a private key from your qt client:
launch your client as usual and wait for it to load the blockchain and start up
click on 'help' in the menu bar (top right)
click on 'debug window'
select the 'console' tab
type: walletpassphrase "your walletpassphrase here" 600
type: dumpprivkey [your btx address here]
this will return the private key, you can copy it now; ensure you clear your clipboard/history afterwards
type: walletlock