Welcome to the forums!
There is usually a blue new discussion button at the top right hand side of the screen in the forum sections. But new discussion threads have been restricted for new members. You are unable to start a new thread until you become a full member . This has been brought in as a result of spambots.
You need to have 50 points and 30 posts before you can become a full member and can then post pictures, have a signature, start new threads, edit posts , post links that show up correctly and change your profile picture.This thread explains about it.