To create the actual sequence, I'd suggest running the someone home helper which will create the overall structure of the sequence for you.
Once you've run that, you'll need an app on the phone of each person you want to track so SEQUEmatic knows how many people are home. Quite a lot of people use IFTTT for this. You can find a tutorial here.
If you don't want to use IFTTT, others have used Automate and Tasker (Android) and also Locative (iPhone) in a similar way. I don't have any tutorials on the site for those apps, but if you work through their respective 'getting started' tutorials you should be able to work it out.
Let me know if you need any further help.