Well. I applaud you for going out there and FREDding your first mission. I hope you'll stick with the hobby, and keep growing as a FREDder.
Now, this is a quite solid first mission. Good basic idea, lots of stuff happening without feeling overwhelmed, the action flows fairly smoothly through each unique phase of the mission, good attention to continuity, and the dialogue sounds like what
Now for some constructive criticism. Don't be disheartened; FREDding is a complex and polished art.
-Briefing's too long. Make the briefing too long, and players will just skim or skip it. You don't need to lay out each phase of the mission in exacting detail; just cover the points which the player will find most important. This applies to FREDding, and to all forms of art in general; trim anything that slows the flow of the mission/narrative.
-Make sure every message is accompanied by "emptymsg.wav", the generic message beep. It alerts the player to focus on the incoming messages.
-Put a delay of, oh, 8-10 seconds between each message. I noticed the messages scrolling by too fast to easily read.
-Attach a hotkey to each enemy bomber wing (or any other mission-critical wing.) Choose a hotkey for each wing from F9-F12 in the wings editor, then write that hotkey in the wing's corresponding directive field in the events editor.
-The first enemy wings take a little while to get to the player and the Warspite. Maybe pull them a couple klicks closer to you at mission start?
-Alert the player that an enemy bomber wing is attacking the Parapet. I didn't notice the Parapet was under attack at first.
-After you disarm its beams, the Normandy just sits there and lets two corvettes beam it to death. Maybe have the Aquitaine jump in instead of the Parapet, so the Normandy dies faster? Or have the Normandy turn around and bring its other beams to bear?
-Maybe have the Normandy's CO deliver some pompous NTF speechifying at some point?
Other than that, pretty solid mission. Will hope to see more FREDding from you in the future!