The chat feature is the feature represented by the speech bubble next to the search bar on your Incenteev platform!
Once you click on it, a new window will appear, showing you all of the old conversations that you have had, classified from your newest conversations (on top) to your oldest ones (on the bottom).
In order to start a new conversation, just click on the upper right button that says "New Discussion" then click on the name of the person (or the group!) that you would like to talk to!
And off you go :)