where do i edit the html on the headings?

if i go to all tpl files,controllers ect there is no html headings to edit, just if statements and php code.

if i go to google inspect i can edit what i want but cannot find the same code in ftp?

i want to add this code to my box headings:

<span style="color: red; font-weight: bolder;">Boats</span>

any help