With guitar it's important to walk before you run. Learning a simple, familiar tune is one of the best ways to get your fingers used to playing guitar. So here we play 'Happy Birthday' - a tune most people know.
Place your thumb in the middle of the back of the guitar neck - that means that your fingers can put more pressure on the strings when you play the notes, because of the opposable strength of your thumb.
Keep your 1st finger (red dot) ready to play notes over the 2nd fret, your 3rd finger (green dot) over the 4th fret and your little finger (yellow dot) over the 5th fret. Whenever you play a note, drop your finger onto the fret, just behind the fretwire, and apply enough pressure to make sure you get a clean note, not a buzzing / muffled one!
If the tune is difficult, just work on it a few notes at a time. Once you get those few notes right, then work on the next few notes and so on.
You only need to play the middle 2 strings - the D and G strings. Pay attention to the picking hand, using the correct direction of the up / downstrokes will help you get faster with practice. In this example, each stroke alternates - down / up / down / upstroke per individual note. Use the Light Strings option (from the Menu bar at the top) to help you see the strings as they are played.
Loop the ActionTab and play along with it when ready, and when you get faster, start practicing along with the normal speed version to check your progress!