It's kind of a funny process... to sign up, you need to go to the website and first ask for an invite. You'll get a confirmation email, and then an invite email with a link to set up your account. I do believe that you have to sign up through Facebook (with Timeline) or Twitter for some reason. I only just signed up myself. After the rigamarole, it is a pretty cool way to collect and share what catches your eye - crafts, recipes, jokes, photography; and it all links back to the original source. You can also find friends who use it, follow their pins, repin other posts that you like to share with people who follow you, etc.
A stubborn horse walks behind you, an impatient one in front of you, but a noble companion walks beside you ~ Unknown