I just realized that the buttons for new threads and new replies are difficult to see. When you view a thread, you should see buttons called 'newpost' and 'newreply' on the upper left of the main body of the thread as well as on the below left.

thanks...i didnt watch it at first...but it was mainly cause i was trying to reply in a locked thread but now i can post

Hehe, no problem. BTW, the FAQ section available in the top bar next to "Calendar" offers helpful info on getting familiar with phpBB. It is a bit complicated, but very powerful.