[TYPO3-english] Typo3 change format Subheader tt_news

[Gerth Jna]

Hello,

I'm new to Typo3 and trying to find a way to change the format of text in the Subheader. I want to change it from "H2" to the class "Subheader"

Is there someone who can tell me where I can change this. What file, of where in Typo3?

Thanks,
GJ