Nice to @ you
Once you've followed a few people, you'll probably want to respond to what they're saying. You can do this with '@replies' . They're called @replies because an @ symbol followed by a username notifies that person that your tweet, which everyone can see in your feed, is a reply to their tweet.
Although you can simply type out '@username', the quickest way is to click the arrow on the right-hand side of a tweet. Click the arrow of the specific tweet you're replying to, because when your tweet is posted it will link back to that tweet. If you don't link to the right tweet it could confuse people trying to follow your conversation.
You can place @username anywhere in your tweet -- it doesn't have to be at the start. You can also add multiple @usernames, but they will eat up your 140 characters.
If someone sends you an @reply, you can see it by clicking on '@replies' in the sidebar. For some reason, you can only see this on your homepage, and not on your profile. It can also be easy to miss @replies, because Twitter doesn't show you how many you have. Unlike DMs...
