help with "every rose has its thorn"

Make your G with your pinky on the first string third fret. When you change to C leave your pinky right where it was on the first string. Sounds nice.
Play along with the video on u-tube enough times to get yourself doing it right.

Finger your G 320033 and then when you go to Cadd9 you just drop the top 2 down a string to x32033     Then when you have to change to the D you can keep your ring finger anchored on the b string 3rd fret and only have to place 2 fingers.  Try strumming dduudddu on each chord and then changing.  Start slow to get used to the pattern and as you feel comfortable with it pick up the pace.   Don't try to rush it!

I never get too hung up on playing it just like the artist...   I play this one with just G, Cadd9 and D with the rare Em and I think it sounds just fine   As for the solo parts, unless you've got someone to play over you, shorten them to just like one round of the progression and then get back to song...  Good Luck!

You have 6 spots  xxxxxx   Each x represents a string.   x  x  x  x  x  x 
                                                                                 E  A  D G  B  e

The numbers represent frets....

x - string not strummed or muted
0 - Open string (not fretted but still strummed)
1 - First fret
2 - Second fret
3 - Third fret
ETC...

So a Em would look like 022000,  a G could be played 320003 or 320033, Cadd9 is x32033 and a D is xx0232

Hope that makes sense....

And yea it's mostly just G and Cadd9 back and forth