With the Instantgo chats, you can easily charge for the messages you receive and reply. In order to get paid for chatting, you first need another user to start a chat with you. By being the first to send a message, that user is the "requester' and therefore will pay for the messages you reply.
After setting up your price per message in the Settings (a message is 160 characters), you will be able to charge for your conversation with another user directly from the chat room. Everytime a user send you an additional message, they will need to pay for it.
In order to charge for the messages that you have replied, you will see a "$" sign appearing on the top right of the chat screen. By clicking on it, you will be able to charge that conversation if you have reached the minimum amount to start the billing process (the minimum amount is 2x your minimum rate per message).
Whenever you complete the billing process, the balance of the discussion will be brought back to $0 for the two of you. At that point again, the first to send a message will be the "requester" and will pay for the new conversation until next billing. Only the person who is charging for its messages can complete the billing process.