You have to integrate it in Xcode/Eclipse. Don't know about Firebase but OneSignal can be added without a problem. There are tutorials here on the forum. A little bit old but the same principle still applies.
Thanks my friend, i find this tutorial : https://www.buildbox.com/forum/index.php?threads/push-notifications-onesignal-android-tutorial.7404/ but not show images, can you upload again images?