i just startet playing wow and i have decided to build a dwarf paladin tank.
but what skill would you choose?

What are you planning on tanking? Dungeons? LFR? Raids?

I'd recommend checking out the guides on Icy Veins, they are usually developed and maintained by players from the highest ranked guilds in the world.
http://www.icy-veins.com/wow/protection-paladin-pve-tank-guide

I've been playing pally tanks since WotLK, feel free to ask any questions

if you're a beginner don't roll tank. roll a DPS class first and observe how tanks tank. then roll a tank second.