On your device (phone or tablet), you search for the Tinder app in iTunes or Google Play. Here you can select the app and then install it. The app is free to use.

After installation you havo to login with your Facebook account. You can do this by clicking on the button Sign in with Facebook. After that you have to verify your mobile number by SMS. Enter your number and you will receive a code that you then need to enter in your app. After that you can use Tinder.