Hey EsmBoone! The forum does take a bit of getting used to, if you get lost you can just click either the "Forum" button up top to go to the main forum page or click on one of the sub-sections underneath the topic title, eg. on this page underneath "Ask your FIRST question..." there's "Welsh" and "General / Questions" (as well as the "home" icon at the very left). Clicking these will take you back to that forum page.
The section on the right is a preview of how your post will look. If you don't add any formatting, it'll look exactly the same as what you've typed, but if you add some formatting like
this you can see how it'll show up (and also make sure your formatting is correct).
EDIT: Also, the reply button at the very bottom (next to Bookmark, Share, Flag, etc.) will reply to the topic as a whole. If you want to reply to a specific person, you can click the reply next to their name (that person will also get a notification that someone has replied to their post and make it more likely they'll see what you've written).
If you want to quote someone, you can just highlight the portion of their post you want to quote and click on the "quote reply" button that pops up. eg:
It's the preview panel!