You can follow the progress of your missions from the proposals tab in the left column of your interface.
A mission to do is a mission that requires an action on your part to move forward : new mission, reply to a negotiation, text to be submitted for validation, to be published...
You have submitted a text for validation, the advertiser would like you to make corrections.
You don't have to do anything, an action is required from the announcer for the mission to move forward. Do not publish. (the advertiser does not validate the text)
You refused the mission or it was cancelled automatically. There's nothing more to be done on this mission. You can still contact the advertiser via the messaging system.