Hi,
In case you're unfamiliar with Regex here's what you would use to insert the 'class=' stuff in the <p> tag:
Select Match case, Minimal Matching and Regular expression. Also Direction 'All' and Look in 'All HTML files'.
FIND: (\<p)(\>)
REPLACE: \1 class="blah blah"\2
Note space between '\1' and 'class...'
For other tags change the 'p' to 'h2' etc and amend "blah blah".
Having said that, there doesn't seem much point doing this if all the <p> tags are using the same rule as you'd just have one css rule for 'p'. Guess I got carried away with a Regex puzzle! Sorry.