Here's a tip for you: If you want to reply to someone's post click and drag over the text to highlight the part you want respond to.
A little dialog box will pop up with the option of quote or reply. If you select reply it will automatically put that in the "reply box"
I prefer to the quote option. With the quote option you can select multiple text and from different messages, then you would go to reply box and you will see a little box that says "insert quotes"
It will show up like this. Also, when you "quote" someone they will be notified that you quoted them.
Hope this helps. 
You can also click on the little smiley face to insert fun stuff.