You can make a list of your favorite songs. To add a song in favorites follow these steps:
Open the app in your smartphone.
Search for the song you want to listen and play it from the displayed result list.
Now you can see that song is playing at the bottom row. At that row, there is a heart sign in the right bottom corner. To add that song in the favorite list, click on it, as shown in below image.
Now the heart will be in orange color, showing that the song is added in the favorite.