First you'll need to get WinAuth

http://winauth.com/download/

For now, as of December 22 2015, you have to use the beta version of WinAuth version 3.4.23

If you're using an older version none of these options will appear. If you don't see them use the absolute latest version of WinAuth. For now that means you need to use the beta 3.4.23

Run the winauth.exe



Click "Add" then "Steam"



Type in your Steam Account name and password. Then click Login



You will now receive a SteamGuard code in your email. Type the SteamGuard code you get into the box and click "Continue"

Skip this section if you already have a phone number registered with Steam


To use the Steam Mobile Authenticator, even on WinAuth, you need an SMS phone number registered on Steam. If you don't you will get the following message after the step above



You'll need to register a phone # on Steam before you can proceed. My guide below has a section on how to add a phone # to your account

Refer to the section "Adding a Phone Number to your Account"

http://steamproxy.net/sharedfiles/filedetails/?id=495405494

Then proceed on with this guide

You'll now be prompted for a code that you will receive via SMS

Put that SMS code into the "Confirmation Code" box which is circled in yellow



Now refer to the red circles

This is your R-code

If ANYTHING happens to your authenticator you MUST have the R-code.

Place this code somewhere safe and separate from your computer

Check the "I have written down my revocation code". You cannot proceed until this checkbox is selected.

Click "Confirm"



Click "Close"

I am not kidding about this. If anything happens to your authenticator you NEED this code.

If you don't have it, you'll be reenacting "50 Shades of Steam Support" for 8 weeks

You really don't want that

These steps are NOT optional. You MUST do these otherwise you are defeating the entire purpose of why you're using the authenticator.





You MUST check the box for "Protect with my own password"

If an attacker hijacks your computer and this is NOT checked off, they can
1) extract your R-code
2) create an exact duplicate of your authenticator

Now your attacker can log in, as you, anywhere they want. Does that sound awesome? Yeah didn't think so.


By now your attacker probably has hijacked your steam account and your email.

Don't be a fool. Make sure the password you use for WinAuth is DIFFERENT than your Steam or email accounts


For double protection you can encrypt the files using the local account and computer.

Note if you do this, if you MUST disable this feature before reformatting your system, or you can't recover any WinAuth settings.

Right click on your authenticator and select "Confirmations"



Log in using your Steam username and password


I repeat DO NOT CHECK THAT BOX

Why? Because once I own your PC, and if you already have Winauth open, you are screwed. I can 'confirm' any trade I want because you let me do it.



From here you can now confirm any trades you have

If you forgot your R-code and want to see it to write it down again you can do so.

Right click on the authenticator, select "Show SteamGuard and Recovery Code"



Here you must enter the password you protected your authenticator with

YOU DID PUT IN THAT PASSWORD RIGHT.



Here you can see your R-code that Steam uses, as well as a bunch of other stuff. We'll ignore that for now since really you should only need the R-code.

http://steamproxy.net/sharedfiles/filedetails/?id=495405494

You need to have a set of SteamGuard backup codes in case you lose access to yoru SMS number. Refer to my previous guide on how to generate this

DO NOT SKIP THIS

If you ever lose your phone number the only way to remove it is either having your authenticator running or having SteamGuard backup codes

Right Click in the Authenticator window
Click "Sync Time"


Uninstall DotNET 3.5
Reboot
Install DotNET 3.5 SP1


Install the latest DotNET 4.5.1

Ensure you're running at least WinAuth 3.4.23

Remember most hijacks happen because USERS download some random trojan or click some link. Hijacks don't happen out of thin air.

You are the weakest link in the security chain.

Dont download shady garbage from teh internet

Dont click on random links from 'friends'

1) You MUST use the password protection security on Winauth
2) WRITE DOWN YOUR R-CODE
3) DID YOU WRITE DOWN YOUR R-CODE?
4) SERIOUSLY WRITE THAT R-CODE DOWN!!!
5) Generate a set of Backup SteamGuard codes in case you lose access to your SMS number
6) WinAuth can't protect you from yourself. Don't download crap from the Internet