A basic site can be constructed completly from
html but to incorporate some flare and features i highly recomend
javascript and
css - cascade style sheeting as well. If you are obsessed with programming and tables and neatness, you may also wish to learn
php,
perl and even possibly
ruby. But i would stick with the first 2 or 3 listed to get it started
You can sign up to many sites which already offer templates for forums etc similar to this one or many other styles.