Guild Wars 2

I’ve come back after an absence of playing to discover a new achievement for WvW tournaments
How do they work, when do they run, how can I participate, ect ect?
Any information is greatly appreciated

Hi guys i haven’t played gw2 for at least six months and decided I wanted to come back.
I’m mainly interested in roaming around WvW and a little PvE content. I have a main thief who was max level but im not sure if i want to keep playing him or if i want to roll a ranger to roam around WvW.
I tried to design a build for the thief for WvW if its terrible let me know, or if you have any other builds you would recommend trying. All of the above would be super helpful.
This is the build: http://gw2skills.net/editor/?vYAQNAoaVlsMp7plOxyJ8PNhs9onqQei7hFCVNlWBaC-zkCBYLCiEEgkFBKRqIasVkDRrWNsKJYqSLqWvCwboIa1AA-w

I chose the armor that wasnt as good as the ascended because I hadnt progressed that far in game yet. I also chose assassins armor due to high precision giving more health, is this bad or good, should i stick to berserker?
Any help is greatly appreciated