Here are your first melody tunes to practice. Listen and get used to the song. Once you have mastered the tunes try and play along to the songs.
It takes time. Try not to miss out tunes and only move on once you have perfected them.
Total Beginners start here:
Ok, you should be in tune. Lets start with these basic melodies. I know they are not cool or exciting, but master these and you will very quickly be playing faster better more modern tunes. Listen, learn and try and play along with the tracks.