Guild Wars 2 - Beginners Tips Needed!

Hello friends,

So I have been playing GW2 since Saturday, and have racked up about 15 hours on my Silvari Ranger, now level 21. The issue is - im terrible at the game. I keep going down and dying, even when fighting a small number of enemies at once. Im not sure if its that the Ranger is a particularly hard class to play, im using ranged weapons so generally im just retreating from enemies and trying to take them down, but im getting consistently outclassed, even when I go to areas where im downleveled.

So im hoping someone will have some useful beginners advice for me. Im not overly experienced with MMO's so im wondering if there is just some basic knowledge or tips/ advice that any one has for a new player?

In particular - one of my main questions is to do with gear. So far I have just been using drops from enemies/ personal story quest rewards. Most items are 'required level' of around 15 - should my gear be more in line with my level, and if so, where should I be getting them from? Also, I have got some level 20 gemstones, but I can't seem to add these onto my items, which wasn't a problem before.

Thanks for taking the time to read this, hopefully someone will be able to help me on my quest!