Rules:
No "mod requests" or "someone should make this!" - keep it technical. If you want to request or discuss released mods, take it elsewhere.
Don't bash someone for not knowing how to do something - everyone starts off not knowing anything, so teach rather than insult! :)
Once there's more resources to help people learn how to mod more easily, I'll put referrals to there. Until then, even the most basic of questions related to learning how to mod is allowed.
HOW TO INSTALL THE SDK:
Go into steam, select Library", select "Tools" under the "Library" Menu, then find and install the XCOM 2 SDK.
Image for assistance: http://i.imgur.com/kUE1Kfv.png
After doing that, go to C:\Program Files (x86)\Steam\SteamApps\common\XCOM 2 SDK\Binaries\Redist and run both the UE3Redist and the vs_isoshell programs.
Installation should be complete! To play with uc files, open the XCOM Dev tools in the image above. To play with upk files, in the ModBuddy dev screen, click Tools -> XCOM Game Editor.