First, it's Factions, not fractions. Now, if you make a PvP character then you'll start off at level 20 and will only be able to fight against human players, you will not be able to play the story mode. When you make a role-playing character you will start off at level 1 and will be introduced to the basics(you can skip the tutorial if you want), and you will be able to play through the entire story. It'd be best if you made a role-playing character and went through the tutorial since you're new to the game.
Now, for a little extra info about the GW experience, mainly the experience with other people. PEOPLE WILL TRY TO SCAM YOU. If they say something like "WTS Super rare bone staff x-damage, x-requirement for 30K" it's a scam. They take the weapons from the first Guild Wars and bring it over to Factions and try to trick you into thinking it's a good weapon, it's not. You'll also hear about people "running" others to new towns/outposts/missions. NEVER pay up front because 70% of the time they will run away with your money and you can't do anything about it.
I'll try to answer any other questions people may have.