Powershell has had a lot of changes since that series so you can run into issues like that with older articles.
Those modules have been replaced with SQLPS. And then SQLPS has been replaced by SQLServer. But you can still use the older modules.
For SQL Server, most things use SQLPS, some starting to use SQLServer. It gets fairly confusing with all the different versions, modules but that's another story.
You should be okay if you import SQLPS. So just try: Import-Module Sqlps -DisableNameChecking
The documentation for this is here:
Import the SQLPS Module

You might want to start with the MS documentation on Powershell for SQL Server as it's a bit more current and does go through loading this module as well as SMO assemblies. It's not you, it's how the changes have been managed with Powershell and the modules that have made it more difficult than it probably needs to be.
 SQL Server PowerShell

Here is an article about the SQLPS and SQLServer modules that you may want to check as that is something you would want to be aware of:
Out With The SQLPS, In With The SqlServer

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