That's great and all, but where do I go from here...
It really is tough, deciding which race to play. Personally, I chose to play Protoss back when I was playing Starcraft: Broodwar because I thought they looked the coolest, then fell in love with their mechanics (the way the race works). What your decision will come down to is likely going to be one or more of the following options:
Your friend plays a certain race, so it will be easier to learn
You have a favorite professional player, so you want to model them
You sit down, try all the races a couple times, and see which one you enjoy the most
If you are to take anything out of this, get the following two points locked down:
You are going to suck. So many people see their friends or professionals play and think, psh... that looks easy. Starcraft II is a very intricate game- you will not be able to master it in a matter of weeks.
Once you find a race you like, stick with it for a while. This isn't a permanent thing- you can change your race at any time! However, it is best to choose a race and play it for a little while until you at least get the mechanics of the race down. I say this because the mechanics of one race often spill into the other races, more or less. It is much like learning new languages; once you have learned German, French and Spanish are a lot easier!
If I can give you one final piece of advice, it is this: repetition, repetition, repetition. Practice your game opener (about the first 6 - 8 minutes) a lot when you first start. You will see exponential progress until you've gotten your build ironed out. There is no shame beating on an easy or very easy computer 10 or 20 times until you feel solid- I do it all the time when I am learning a new peculiar build.
Okay! I'm feeling like I know what race I'm gonna start with!
Wait wait wait... what the hell is a Nexus? I just made a building as zerg... where did my drone go? I'm playing Terran and I just got into Masters league and all I did was spam Marines... how did this happen?
Starcraft II is a pretty in-depth game, and I guarantee you are going to feel in over your head when you start. Don't worry about it, every player was there at some point, I promise : ). Take a deep breath, my friend, you've got a little more reading to do before you're ready to dive into the battle of Starcraft II. Here's a few ways to start getting your feet wet.
Watch some streams and see how the Pros do it! Go to Team Liquid's site, scroll down a bit and look to the right, and you can see a list of professional players streaming their practice! If you want some commentated games, you can go over to the VODs page.
Go to the Community page and get in touch with some of the players! Find a practice partner or even a teacher there. We are all more than willing to help you out on your journey to the top : ).