It's very simple if you have already set up your Nano S either ledger live or Electrum.
If you did not set up it yet read this basic guide below
- Set up a new device (Ledger Nano S) with Ledger live
- Set up and use Electrum with Ledger nano
Take note you must save the seed or 12/18/24 words backup to a piece of paper or any safe place because you can use it to recover your wallet in the future.
Now after you set up them generate an address from Ledger live to make sure it was a BTC address or in Electrum and then copy the address go to your "bitcoin wallet" where the BTC that you want to transfer paste the address there and send the amount your want to send.
Or you might be talking about transferring them and use the backup seed from your Bitcoin wallet and import it to ledger nano?
If that's the case you won't be able to do that.