Help ..... how do you reply to someones post?

As I am new to this I am a bit stuck on how to use it lol.... can anyone explain to me please. xx

Right above the last post are options "reply" and "quick reply". Press one and a box will pop up to type your response. I usually use "quick reply" because it's faster....it has none of the options for adding photos, links, or emoticons though.

Thank you very much x