How do I authorize my computer for past purchases

Authorization

Macs: iTunes Store- About authorization and deauthorization.

Windows: How to Authorize or Deauthorize iTunes | PCWorld.

In iTunes you use the Authorize This Computer or De-authorize This Computer option under the Store menu in iTunes' menubar. For Windows use the ALT-S keys to access it. Or turn on Windows 7 and 8 iTunes menus: iTunes- Turning on iTunes menus in Windows 8 and 7.

Also see, iTunes Store- Authorize or deauthorize your Mac or PC

Is your computer authorized at all? If not, open iTunes and click Atl-S to open the Store menu, then select Authorize This Computer.

I can't find a place,Icon, instructions (except outdated ones) or any other REAL information which succinctly guides me to be able to authorize my ...ahem, ASUS laptop.