As likely as not, you will need to contact people about the work. Each task has an Open chat option, which you can find from the : menu or the Messages section on the task.

Chat sent by task owner

If you haven't connected to the person before, you will only be able to send them chat messages once they have agreed to connect.

As well as sending messages, you can use chat to share any types of file. You'll also see all the status updates in the chat.