Some resources that may help for general tanking tips. These helped out a lot when I first started. Some of it seems complicated at first glance but it'll soon become second nature to you.
http://i.imgur.com/smNx1ZX.jpg
https://i.imgur.com/PEnLMF9.jpg
This is a little old but may be useful.
https://www.reddit.com/r/ffxiv/comme...ing_resources/
Your gear will likely be your biggest hindrance in tanking low levels. You may be adequately geared for the dungeon but your gear will be outclassed by a level 60 level synced; if your gear isn't the best you can get for your level then you'll be at a slightly bigger disadvantage.
Assuming all your gear is at level then you have 3 options to choose from: NQ, HQ and dungeon drops. NQ will offer you the worst stats of the 3, it may be serviceable but its not going to help you much. Dungeon drops will give you pretty good gear and will help a lot but HQ will generally give you better stats and the option for melds. Again, assuming its all same level gear. There's going to be two main differences between your gear and a synced level 60. The first is that you won't likely have good gear in all your accessory slots (some of it isn't available) where as a level 60 will have them all. The second is low level gear often doesn't have a lot of secondary stats on them where level 60 gear does. While you won't necessarily be hindered by not having them, it does give level 60s a slight dps advantage over you.
Its those small differences in gearing that allow level synced players to get away with some of the things you're struggling with. The differencs are slight, and arguably minor but they can be felt. Don't worry, those differences fade as you get better geared and get access to your higher level enmity skills. Lv 50 tanking is much easier than Lv 50 tanking because of it; and level 60 tanking is just awesome.
Also, while every game does have its share of assclowns and people that will give you a hard time of things, if you say you're new and learning still most people are very forgiving of tanking mistakes. Some people are also willing to give advice if you ask for it too.
And, of course, don't be afraid to ask questions here. Most of us like helping new players improve.