If you have iOS device and still haven't received the latest update, you'll have to wait until it rolls out to you. Once you get the Snapchat message and watch it, double-tap to upgrade. If you don't see the "Update" button in the App Store, you might have to exit and enter the App Store itself, then hit the "Updates" tab or search for Snapchat and upgrade.
If you're on Android and you haven't seen the update yet, you can download it from here and manually install it.
In order to start a chat, swipe right on a friend's name from your inbox. If they're not in your inbox, you'll have to send a picture to them or receive one from them. Once you swipe right, you can start messaging.
Just like photos and videos, you can only see your conversations up until the other person views them, but if you stay within the thread, you can keep messaging back and forth until you exit.
To save a specific message, tap on it and you'll see it go bold. This will save the message anytime you go back into that conversation. As is standard with Snapchat, taking a screenshot of the conversation will show a notice in the thread.
Directly through any chat message, you can send a picture to the person you're talking to by tapping on the yellow icon at the bottom right. Just hold down and slide your finger up or down to change the camera view—top half for front camera and lower half for rear camera. If you get any pictures sent to you, you can view them through the chat message as well.
The other major addition to Snapchat is the ability to live video chat with whoever you are messaging with. If both you and the other person are in the messaging thread at the same time, the icon at the bottom left will turn blue.
Tapping and holding the icon will transmit a live camera feed to the other person's device in full screen, while it shows up as a small circle on your device.
To send a live video through your rear-facing camera, hold down on the circle and drag it to the bottom half of your screen. To use the front-facing camera, drag the circle up in the top half of your screen.
After using this updated version of Snapchat for a bit, I noticed that notifications are now aggregated—meaning if one person sends you multiple pictures, they'll all be located in one notification and you can view them as you would a Snapchat Story.
Using both features on the Android version of Snapchat, I can say that the chat messaging worked great, but the video chat was a bit laggy at times. Hopefully they fix some of the issues in the next update.
That being said, these new features are undoubtedly big additions to Snapchat, and for me, means I'll be using the app quite a bit more. Have you installed your update? Share your thoughts with us in the comment section below.