Please take the time to spell out words like "and", "you", "your", and "anyone". In conjunction with careful
spell-checking ("easily"), you can
easily avoid appearing as dumb as a bowl of mice and might get a more helpful answer than what follows.
Anyway, the very forum software you're using right now,
phpBB, uses HTML templates, though they're not trivial to use. For guestbooks, an easy
Google search yeilded no fewer than 20 very promising leads. A similar search will get you going on forums, too, if phpBB doesn't suit your needs.