Microsoft's SDK's, Starter Kits, and Documentation for XNA and MonoGame

XNA.com / MonoGame.net
If for some reason you're new or unaware, XNA and MonoGame are basically the same thing. Anything you can do in XNA, you can do in MonoGame, and vice versa.

IDE's
I highly suggest downloading Microsoft's Visual Studio 2010 Express for Windows Phone, as it gives you everything you need to start using the IDE and XNA for Windows, Windows Phone 7/8, and X-BoX 360. For MonoGame, you'll probably want the newer versions found at:
https://www.visualstudio.com/
https://www.xamarin.com/

Documentation
https://msdn.microsoft.com/en-us/library/ff576659.aspx

Starter Kits / Examples
http://xbox.create.msdn.com/en-US/education/catalog/

Conclusion
With Microsoft shutting down XNA and now XBLIG / XNA.com, the main XNA.com website will probably vanish within a year or two. I highly suggest you download everything while you still can.

Good luck with your XNA / MonoGame projects! GAME ON!

Publishing
Once you've completed your game, you can publish almost everywhere using XNA and MonoGame!