For those playing for Time the first Time here's a few instructions / tips for the duel phase and what to do there.
First, you need to schedule your match with your opponent. The best way to do this is via PM.
Before you send any PMs, go to Profile, then Modify Profile --> Personal Messaging and activate "Save a copy of each personal message in my sent items by default".
This will save any PM you send in your Sent Items folder. So if there are any discrepancies with your scheduling, you always have your PMs as backup.
Then send a PM to your opponent. Always give the opponent the Times at which you are able to play. If he has already gives you his, pick one. Always give those times in GMT. You can use an online Time Zone converter for this, but here's a trick I use: Go to Profile, then Modify Profile --> Look and Layout and there set the Time Offset to "0". This will make your personal forum Time = GMT, so to find the current GMT you can just go on "Show unread posts since last visit" and you know it.
Now the next part is important, not all teams do this, but I found it invaluable during my last Wars: Post the time you will play in our round thread. This allows your Teammates to spectate the match. Come to Teamchat before the match. Many of our decks require some strategizing, which is difficult to do when you're playing at the same time. Having a few extra eyes in Chat helps a ton in those moments. Plus it's more fun to celebrate a win when there's more people around.

After deckbuilding phase, you will find your deck in the Vault sheet, in the S/D/C/P/A tab. Before your match try to familiarize yourself with the deck, just a couple games vs AI3 are good already.
Ok that was my stuff, if there are any questions, ask me here or in Chat! Same goes if you have any tips to add of course.