CWallet does not charge any fees when Sending or Receiving the crypto.
However, in order to confirm your transaction in the blockchain, a transaction fee is required. This fee goes straight to miners. The fee is calculated automatically by the app, according to the current network load, and can be changed from one transaction to another.
When you send your crypto, you need to make sure you have enough funds in your wallet left to cover the transaction fee. If you don't have enough for the network fee, the app will automatically show you the error.
If you are an advanced user, you can change the network fee, choosing the custom - be careful as not enough fee can result in declining your transaction in the blockchain.