Congratulations on your first dungeon and welcome to the world of tanks! It can be a brutal world out there, but we're all thankful we have someone like you to take the hit for us. Please keep that small comfort in mind, even if it doesn't always seem that way.

As for tips:

As you gain levels, you will eventually gain access to more of your damage combos. Early on, it's easy to simply use your enmity combo. However as you play tank more, be aware that extra enmity does little good. You only need enough enmity to keep the enemy's attention and can output the rest as your damage combo.

If you have the chance, try to play a healer and gain insights into how they play. As a tank, you rely on your healer quite a bit, and the healer spends a large amount of their attention on tanks; so playing as a healer can teach you many tricks other tanks use (such as CD and positioning) that you might not normally see as a tank. Healers also have decently fast dungeon queues, so it's not hard to level up solely in dungeons and use the experience to supplement your tanking or techniques.