Since you are using an online wallet, in this case you do not have access to your private keys. It is important for you as a beginner to secure your online account with a strong password and 2FA, and not to store this information online or to make it accessible to others. It is also important to save your seed (wallet backup) by following those instructions : https://support.blockchain.com/hc/en-us/articles/209564506

In case you want to have full control over your private keys, you will need to install something like Electrum wallet (desktop wallet), but always be careful and make sure you download the files from the official site : https://electrum.org/#home