Unfortunately, in order to post in the #live:events and #live:groupflights Category, you must increase your Trust Level (TL). They include Basic (TL1), Member (TL2) and Regular (TL3).
You are not in a Trust Level at the moment because you are a new user. You have joined this forum two days ago. In order to increase your TL, you must engage in this community more often. This includes liking posts (heart), commenting and creating interesting topics over the period of days or weeks.