You can insert emoticons or "smileys" in two ways:
Type in a symbol. For example, type in a semi-colon followed by parenthesis ;) and when you post the reply, the readers will see the graphic winking smiley face. The emoticon will not show up graphically as you type the reply, only after you post it.
Use the smiley face menu. Click the smiley face icon above the reply field and select the emoticon you'd like to insert. The graphic smiley will show up in your reply immediately.