Very new at playing guitar and whenever I play chords I can't seem to get it to sound very similar to the song. Songs like All Along the Watchtower and Wish You Were Here with basic chords. I am fairly sure my guitar is in tune. Any tips for what might help me get on the right track.
I am fairly sure my guitar is in tune.

Be 100% sure.

Are you by chance playing a nylon string guitar? If so, thats natural, they have a characteristic sound and you wont be able to perfectly replicate sounds a steel string guitar can make.
First, get used to playign those strings. Develop the callouses you need.

And then, get your fingers used to the fretboard. Once you get the feel, playing chords will be really easy.
And practice daily, play basic chords like C, D, Em, G Over and over..
what exactly sounds different? do the chords not sound good or have you just not gotten to hang of strumming in rhythm yet or what?
There's a few possible culprits.

1. Your guitar could be out of tune

2. You could be playing the chords incorrectly

3. If you're going off Tabs - they are frequently wrong, or sometimes in keys other than whatever recording you are listening to.

4. Any combination of 1, 2 & 3....
it's possible that you're playing the right chords, but you just need to clean them up.
Sorry, I'm sure this has been posted elsewhere but I wasn't sure where to look.

When reading the chords for music on this site G* keeps popping up. How should I play this chord, is it different than just G?

That's probably the tabber's way of saying use an alternate G - could be the barre version, or they might mean 320033, which is a G which a lot of people like as it sounds a bit "fuller" than the regular 320003.