You should be able to play this song in less than a week, if you can't, please play songs from level 2
The best way to learn this song, or any other song, is to watch the video at least 10 times, if it is necessary, please watch the video more times, until you feel that you understand the song, and you are familiar with the tune. Concentrate on the notes on the fretboard to see where you have to play more or less, then look at the numbers on the TAB, feel the music and try to sing along with it. Once you start to play the song, feel free to come back to watch the video more times.
Once you are familiar with the song, and how it sounds, then print the music score PDF below.
Now, with the actual music sheet on your hands, play the video a few more times and put your eyes on the paper, and read along with the music, listen to the song while looking at the music sheet. Now that the songs are a little bit longer, it's very important to understand how to study better.
Count the measures in the song, the same as you did it in level 1 and level 2. Some songs have chords and melody. If you know the chords you can play the song using the chords, and if you don't know the chords, don't worry, just play the melody, in level 4 we will start using a lot of chords.
FIRST: PLAY ALL THE NOTES ONE BY ONE. I guess you are reading TAB more than music notes, so just play each number once, from beginning to end, do this at least 3 times.
SECOND: LISTEN TO THE VIDEO AGAIN. After watching the video one more time, try to get a little bit of the song at a time, a few measures from the beginning, play it over and aver to get the right timing. Once you have the first phrase go to the next, and the next. Each day you have to learn so many measures, or a part of the song. DON'T LOOK AT THE WHOLE SONG, IT WILL BE TOO MUCH.
THIRD: Start playing the whole songs, SLOWLY. It's better if you play really slow each note and make sure you are making the right sound.
Play only 2 or 3 measures or any part of the song for that day, think of it, as the complete song. Play it over and over and practice until you can play those few measures. If you get tire of practicing, take a break, and then come back to keep doing it.
Once you can play those measures without mistakes at least 5 to 10 times. Then relax, and the next day do the same, with the next few measures. If you practice like that, steady and constantly everyday, you will learn to play the song, and you will be able to play the guitar much better