For starters, if nobody died and you guys didn't fail then that is good for a first timer.
As for rotations for MRD at your level see the above post by Anuri.
Other things to keep in mind as a tank.
- You are typically the de facto leader of the group and are expected to know the dungeons and boss fights. If you don't, it is better to let the group know you are new to it than to not say anything. But as a tank you should make it a point to learn and know the dungeons and boss fights.
- You need to mark mobs in dungeons. If you are not familiar with this, marking is where you "label" enemies with numbers and symbols to let the group know what the plan of battle is, for example labeling the first monster for people to attack with "1", then the next mob to go to with "2", etc. There is a menu that you can bring up that is labeled "signs" or something like that that will have sets of numbers paired with symbols that you can assign to ability bars. When you use that symbol as an ability with a monster selected it will cause that symbol to appear above the monsters head for the whole party to see.
- Know your enemies. When you are running a dungeon, you need to know which enemies are the priority targets that need to be dealt with first. This will make it so that you mark monsters in the proper order and take out the more troublesome ones first.
- Know how to position monsters. A lot of monsters will have AoE and Cone attacks that are telegraphed by red on the ground. You need to get used to positioning yourself so that when the monsters try to do one of these attacks, that it will not potentially hit your party. In order to do this you will often need to position yourself on the other side of the mob so that it's back is facing the rest of the party or backing yourself into a wall or corner so that again the monster will be facing you and will have their back to the rest of the party. Once the red attack telegraph appears, that is where the attack will land so you are free to move out of that space and dodge the attack without fear of the mob following you and hitting your party. Just remember to move back and reposition yourself after the attack has gone off.
- Get good at quickly swapping between targets. This will help you a lot in many different ways. It will help if you suddenly need to switch targets to change out marks for different priorities. It will help if a mob suddenly breaks off and goes after someone else and you need to suddenly switch targets to grab hate back. It will also be invaluable when you need to cycle through targets to build up more hate on them because you have your dps AoE'ing the whole group.
- Last but not least, keep a cool head. An unfocused tank will get their party killed.
Sorry if this seems like a lot, but these are some of the basics that every tank should know and be very comfortable with.
Tanking may seem tough and may be overwhelming and seem like a lot to have to learn and keep track of to a newcomer, but if you stick with it and get good at it, it can be incredibly fun and rewarding.