Obviously, the first thing is to create your free IFTTT account.

Once you are logged in, you need to select the "My Applets" link from the main menu:

On the next screen click the "New Applet" button ...

... which will bring you to the create a recipe wizard. Now you need to choose a trigger by clicking on the blue "this" link:

You will see a bunch of web channels that can be used with IFTTT. Simply type YouTube in the search bar and select it:

You'll be taken to the next step where you need to connect your YouTube & IFTTT accounts.

Click the "Connect" button, select your targeted Google account and click the "Allow" button to allow IFTTT access to your YouTube account:

Once you have activated your YouTube account, you'll have to choose a trigger.

In this case you want to select "New public video uploaded by you" ...

Usually, this will bring you to the next step which will allow you to choose fields from your selected trigger.

However, in this particular case the trigger doesn't have any fields to choose from.

So you'll be taken to the next step where you need to define the THAT part of your recipe ...