I am new to VGC 2012 as well. I'm also new to Smogon, but I've lurked for a while now and know a little about VGC and teambuilding. The first thing you should know is that you want 6 pokemon because of the Team Preview option this year.
On Landorus, you should put Protect over Sandstorm for defensive predictions, and either put Explosion or Hammer Arm over Brick Break. Also, you might want to put a Yache Berry on it to help it survive some Ice type moves. The "Increase" in stats you talk about are EVs. There are a lot of articles on EVs throughout the internet, but basically they are things you get when you KO certain pokemon. Some increase Attack, and others increase HP. There are EVS for every stat, but you can only put 255 in each stat. For each 4 EVs, you get on more stat point. You can overall have only 510 EVs, so use them for what each specific pokemon needs. Also, there are certain natures that increase one stat and decrease another. For example, Landorus should either have an Adamant (Atk+, SpA-) or Jolly (Speed+, SpA-).
On Tyranitar, everything looks decent, except for the item. I would use either a Focus Sash to survive at least one hit or a Chople Berry to survive Fighting type attacks easier. The nature should probably be Adamant.
On Rotom-W, I would either use Sitrus Berry or Electric Gem over Zoom Lens. Also You should run a Modest (SpA+, Attack-) nature to increase your damage output. Confuse Ray should either be replaced with Thunder Wave or Protect. And you should use Hidden Power Ice or Grass, which I assume you already have.
And finally, Scizor. You should either run a Steel Gem or Occa Berry to increase the output of Bullet Punch or survive Fire type attacks. I would use an Adamant nature and replace X-Scissor wth Bug Bite because Bug Bite gets the Technician boost, making it stronger. Vacuum Wave should be replaced with Superpower or some other filler move.
I would recommend using the Marriland Team Builder to find weaknesses in your team, and fix it accordingly. So yeah, basically just Google these: Pokemon EVs, Pokemon Natures, and Marriland Team Builder. On Marriland Team Builder, it doesn't support Rotom-W, so type in Lanturn and ignore the Ground Weakness. Hope this helped.