That is your goto website for anything Starcraft related. You can see ongoing streams and tournaments on the right side and of course browse some interesting threads and partake in discussions. That site is also heavily moderated which is why it isn't a complete shithole :P
As far as playing the game goes, I for one would just play through the campaign to understand the basics and... well t's also a nice campaign. For multiplayer you can do stuff like watching pro gamers and just take a basic strategy and try it out for yourself or you can just dive into playing without doing extra research. Depending on how much you like it, you're kinda bound to be interested in reading through some threads so I wouldn't worry about that.
My biggest advice for you:
Enjoy IMPROVING at the game. Don't get mad when you lose. When I'm playing, which currently isn't the case, I love seeing myself improve my gameplay. It just feels good to realize I macro/micro better or just generally have gotten better at controlling stuff.
Do not play to win every game. If that's your goal you're gonna get upset really quickly. Instead try to care little about your win/loss stats and the like and focus on improving. Because that's the best kind of progression!