Help picking strings on the guitar?

You have a simple chord sheet using basic chords, some of the first ones a beginner would learn. I can only assume that what you are trying to do is to play songs on guitar without bothering to learn the basics. As you have discovered, this doesn't work..

It's not complicated at all.

Do you know your basic chords? If you don't, that bit at the top is showing you how to play all the chords used in the song.

From left to right: D, A, Em, G, D/F#. Those 5 chords are the only ones you use in the song.

Tab is written upside down. Think about it like you're looking down at your guitar while you play it. The top line is your thinnest string, the bottom line is your thickest string.

What that is showing you is how to play those chords, and the chords are lined up vertically under the name of the chord.

Let's start on the left with the D chord. That is showing that you want to put your fingers on the second fret of your thinnest string, the third fret of the next thinnest, and the second fret of the one above that, and you play the next string above that without putting your finger anywhere on it. You don't play the 2 thickest strings at all for that chord (that's what the Xs mean).

The rest of the chords are lined up vertically under the name of the chord.

If that is still confusing, you should get someone to show you how to play those chords in person.