So hello. 
 
I've started playing, and naturally, I'm shit. A guy threw a trillion void rays at me, and then another guy just mass marined me, and so on, all the idiot tactics that I should KNOW how to counter, but I just can't. I know a lot of people say "Oh go and watch a replay", but is there another way of trying to apply the things you know into an online game? I try to keep up with everything at once, but it's just too much to handle. I've tried Protoss, and it's the most high maintenance, and Terran felt pretty good, so I guess I'll stick with them for now. The problem is, I don't know when to stop making SCVs, or how many marines/marauders to make before I transition. I've looked on the teamliquid website, and I don't really understand how the build orders work. I always supply block myself, or get pushed early, then lose to like 5 marauders. 
 
Help me out! How do I effectively use theory online when everyone seems to be demonicly possessed by Koreans?

I'd suggest the challenge mode, sure replays help alot but this mode will help with the counters to your problems

Get a practice partner and have them constantly do what you're having trouble with. Like "Hey Dave, mass reaper me for the next 5 games." You'll eventually learn how to deal with it.

 The problem is, I don't know when to stop making SCVs, or how many marines/marauders to make before I transition. I've looked on the teamliquid website, and I don't really understand how the build orders work. 

In Brood War I just learned by getting my ass beat for a few weeks, and then just clicking. 
 
No real way to apply it, just win and get your body to work out the APMs.

@JokerSmilez:

" @Fallen189:  add me and I'll help you out :3 Wunder.528 "

I play Terran, and generally I'm pretty much always training a worker and building a supply depot. If you're producing from three barracks, you will be making troops about as fast as you can build the depots, so just chain build them so you never get supply blocked. You can basically never have too many workers because by the time you get enough to fully saturate your main (around 30) you should be thinking about expanding if you haven't already. It takes practice to get used to the rhythm of making troops, workers, and supply depots as soon as they complete while remembering to scout your opponent and tech up to counter whatever he's going to throw at you, but that's why the game is hard to master.

...people are still posting theory.  It's not the way to help, you need a buddy to help with who is at a higher level.  You can read up everything in the world, but it mostly comes down to the hands and focus.   
 
You could know EVERYTHING about SC, and be a fantastic commentator, but be one of the worst players online.  The real deal is that once you're on the battlefield, it comes down to physical skill and mental knowledge of not the theory but rather what you should be doing 2 mins from now. 
 
The best way to apply theory is to just play.

" So hello.  I've started playing, and naturally, I'm shit. A guy threw a trillion void rays at me, and then another guy just mass marined me, and so on, all the idiot tactics that I should KNOW how to counter, but I just can't. I know a lot of people say "Oh go and watch a replay", but is there another way of trying to apply the things you know into an online game? I try to keep up with everything at once, but it's just too much to handle. I've tried Protoss, and it's the most high maintenance, and Terran felt pretty good, so I guess I'll stick with them for now. The problem is, I don't know when to stop making SCVs, or how many marines/marauders to make before I transition. I've looked on the teamliquid website, and I don't really understand how the build orders work. I always supply block myself, or get pushed early, then lose to like 5 marauders.  Help me out! How do I effectively use theory online when everyone seems to be demonicly possessed by Koreans? "

At least when it first came out (people might be better now) you could get into platinum just by making more stuff than the opponent with absolutely zero strategy. Always make SCVs, always make supply depos when you need to, and always make out of your barracks. If your money gets high, make more barracks.

" At least when it first came out (people might be better now) you could get into platinum just by making more stuff than the opponent with absolutely zero strategy. Always make SCVs, always make supply depos when you need to, and always make out of your barracks. If your money gets high, make more barracks. "

Never stop building SCVs. Never.

basically if you dont dedicate a ton of time to it you will not get very far. thats why i have pretty much quit. i had fun playing until i lost 6 in a row. now its angering the shit out of me. i hate losing over and over again.i try everything. i just lost last game against 6 carriers. i had tons of anti air. tons of  everything.  i was harassing him like crazy. i was doing all the shit everyone says to do but i just couldnt do it. carriers and chargelots and i got destroyed. 
 
either play everyday or get used to losing constantly.

Play in the morning, before go to work. The players online are far easier.