To make Bitcoin transactions with Ledger, you need:
Once these apps are installed, to open your Bitcoin account, just:
This application is an account manager, where you can send and receive Bitcoin transactions and check your balance.
The only way to open it is to connect your Ledger device and enter your PIN code. Without the device, the app won't launch. With Nano S and Blue, you also need to open the Bitcoin app on your device.
For each sending transaction, your application will ask you to verify your transaction. On Nano S and Blue, this authentication is directly made on your device screen. On Nano and HW.1, this authentication is made with your Security card or the Ledger Authenticator.
UPDATES & TROUBLES
The Bitcoin Chrome application updates automatically, you don't have anything to do. Each time Ledger releases an update, it will be synced after a few hours on your computer. If you want to force an update to the latest version, just restart Chrome.
If your Bitcoin app doesn't open, please consult this article.