Welcome to the game!
I'd suggest you look for a guild right away. If you are new that is the best way to learn the game. Ask for a guild open to new players and willing to mentor someone new. If you don't like the guild you can always quit and join another. There is no penalty for hopping from guild to guild.
Best place to find a guild is either "pre" Prophecies (it's starter area) or Nightfall Kamadan (which you go to after the first quick tutorial/easy mission) so I'd create characters in both campaigns to check out the possibilities.
And like said above, go to the American district. No matter the nationality, if you want to find people playing that's where you can find them.
And yeah you can play most of the game alone now with the heroes update so if you don't see as many people in towns and outposts looking for groups that is the reason. Which is all the more season to join a guild right away.
And never forget about wiki. Wiki is your friend and has tips, instructions, maps and details about pretty much everything in GW1. Can't really get through the game without it.