If you wanna play that intro from My Hero here is the tab for you ;)
So in the beginning you play this:
e|----------------------------|
b|------3-0-0-----------------|
g|------------2-0-0-----------|
D|-----------------0h3-5-0-3-0|
A|----------------------------|
E|----------------------------|
[ Tab from: https://www.guitartabs.cc/tabs/d/dropkick_murphys/my_hero_tab_ver_2.html ]
And then more faster:
e|---------------------------------------------|
b|--3-0-0-----------------3-0-0----------------|
g|-------2-0-0-----------------2-0-0-----------|
D|------------0h3-5-0h3-5-----------0h3-5-0h3-5|
A|---------------------------------------------|
E|---------------------------------------------|
In this part i don't know if this is exactly what he plays but this sounds good also ;)
e|-------------3-2-0----------------------------|
b|--3-0-0-5-0-0------3~--3-0-0------------------|
g|----------------------------2-0-0-------------|
D|---------------------------------0h3-5-0h3-5--|
A|----------------------------------------------|
E|----------------------------------------------|