First, go read the rules and follow them the best that you can.
Then, you can head off to any of the individual forums that sound interesting. If you want controversy and heated discussion, then head off to News and Politics, or the science section. If you just want to share anything, or see what's up with others, go to the off-topic forum. Or you can read fanfics, poetry and such at the sunstone gardens.
I should warn you though, that the message board has been slow for quite a while. You may be better off signing up at the Dinotopia Official Message Boards. There's a lot more traffic there.
"It is folly for a man to pray to the gods for that which he has the power to obtain by himself.” – Epicurus
"Every heart sings a song, incomplete, until another heart whispers back. Those who wish to sing always find a song. At the touch of a lover, everyone becomes a poet." - Plato