When you enter a topic/thread and you would like to contribute to the conversation you have two options one is to click the AddReply button up top or bottom of the post or to click the FastReply button at the bottom. We will show you both ways here:

Fast Reply Option
This is best for quick one liner replies and without having the browser refresh the page, at the bottom of the Topic/Thread you will see this button right next to the AddReply button, Click on FastReply

Type your text where stated, and click AddReply
If you would like more options, (bold, image attachment and so on) click on More Options right next to the Add Reply button.