Characters under lvl20 DUNNOT need "builds". Characters under lvl20 need experimenting with as many skills as possible. ANY skill will do fine, when you're under lvl20.
The worse thing at this point that you can do, is use someone elses build and never learn how to actually play the game. I remember when i started Guild Wars; i'd use Ranger with pretty much any skills, and it worked because in low lvl areas anything works (not that PvE in general is difficult, if Mending whammo can beat it).
The only thing i can help you with are tips - study the class, see what strenghts it has, and then increase the strenghts. Dont try to make the class jack-of-all-trades, but do what class is good at, and do it superbly. That being said, dont use horrible skills such as Natural Healing. Dervish is about enchantments. Use enchantments. If you have monk secondary, dont use Orison of Healing like some people do, or you'll see the footprint on your bum after i kick you from my PvE team

Use Reversal of Fortune instead.
In short, you dont have to have an insanely good build, no one is expecting it of you. But you do need to think. If you play Ranger and use spells, you'll also see my footprint on your bum

Same thing.
Rule of a thumb - dont do what other class can do better.
The exception to this rule is ONLY when you're bored of the class, you explored its possibilities, and you want a bit of refreshment. Then, only then, can you start playing D/A assassins and similiar builds.
Have fun exploring the game.