Login to your User Area as usual using your account username and password:
You will be asked to enter the code from the authenticator app.
Check the Remember This Browser as Trusted box if you are logging in from a trusted computer (for example your home or office computer) and do not wish to enter the authenticator code every time you login from it.
Open the authenticator app on your phone and find the code currently generated for your account.
Enter the code in the field provided and press Login. Note that on different devices and application the code may appear with spaces between the digits. You need to enter the code without these spaces when logging in your User Area.