Although this tutorial you've already posted MrPresident works quite well. I know of a different method I will show you now. If I'm not allowed to post here, I apologize and you can remove my post without warning, but if you did enjoy this method, feel free to include it in your original post. You have my full permission.
Pros about this method:This method does not require you to use your developer console, or even go in-game for that matter.
Cons about this method:I believe you will have to have your Steam profile set up for this to work, but I may be wrong. This is not a big issue though, as most people should have their Steam community profile at least set up with the basic stuff (You DO NOT need to fill it out fully).
Things you will need:- A web browser. (For example Internet Explorer, Google Chrome, Firefox or Opera. You're using a web browser RIGHT NOW).
- You need to have Steam open and logged in.
- Basic "Know how to use a computer" knowledge.
Step 1 - Going to your Steam community profile: You will need get your Steam community URL, which you can do using multiple ways as I will explain a bit further down in the post, but for the most part this means that you will need to go on your Steam community profile. If you already know how to open your Steam community profile, skip to step 2.
Going to your Steam community profile can be done in multiple ways, I'm showing 3 methods on the picture below.
Method 1&2 are the easiest, but pretty much the same.
Method 1: You can go on your main Steam window (the one with "Store", "Library" etc.) and click your avatar as shown in the
red square in the bottom-right of the picture.
Method 2: Go on your friends list (you should know how), and do the same as in method 1, click your Steam avatar (Again, shown in the
red square close to the bottom-right).
Method 3: This takes longer than just clicking on your Steam avatar, but still works. Hover over your name (
green square) in the main Steam window, mine is "Decicus" as an example. Then click "Profile" (
red square).
Step 2 - Getting your Steam community URL: Again I have a picture to show what you need to do as soon as you're on your Steam community profile to get your Steam community URL.
Right-click anywhere on the Steam community page and click "Copy Page URL" (
red square).
Step 3 - SteamIDFinder.com: After you've copied your Steam community URL, open up a new tab in your web browser and go to
http://steamidfinder.com. Alternatively you can scroll-wheel click or CTRL + left-click the link for it to automatically open the page in a new tab.
The page should look like this. Click inside the box shown (
red square), and then paste the URL into it (Right-click -> "Paste" or CTRL + V). Then press "ENTER" on your keyboard, or click the
lime-green magnifying glass with your mouse.
After you've done that, you should be able to see some more info about your Steam profile. An example is shown on the picture. Your Steam ID is what is inside the box where the
red square is, as an example, my Steam ID is "
STEAM_0:1:18726919".
The amount of digits may vary depending on when you registered your Steam account (mine is 5 years old, if your Steam account is around 8 years old, you may have less digits after the last colon).
For future reference, if you've set up a custom profile URL (the letters+numbers after the "
http://steamcommunity.com/id/" is your custom profile URL, my example is "FADWAlex"), you can try to remember that as it is possible for you to enter just that in the box where it wants your Steam community URL.
If you've read this all the way through, and you're having problems, feel free to send me a PM and I will reply to you ASAP.
And if it helped you, I would greatly appreciate a "Compliment" through the forums karma system, it took me some time to write this. 
