I do these things with an android control tablet. Look up SmartTiles. I run that, and since the tablet is there I use its capabilities. I know you are a beginner, so let me take you through what I do.
SmartTiles is running on the $40 android tablet. SmartTiles is a web-based info/control screen for SmartThings. Great tool, worth the investment in learning. There’s a newer version out with a different name.
On that tablet I’m also running an app called Tasker. Tasker allows you to automate activities on your android phone or tablet. When X condition is met, Y action occurs.
There is a Tasker plugin that bridges between SmartThings and Tasker. It is called Sharptools. It allows SmartThings events to trigger things on the phone, and it allows things on the phone to trigger events in SmartThings.
So… one example I have is my washing machine. It’s power usage is monitored by a smart plug. When that plug falls to zero watts, it indicates that to sharptools. Sharptools then triggers the android tablet to a) turn up media volume, b) announce “laundry wash cycle is complete”, c) turn media volume back down.
Obviously, such things could be triggered by a door opening - so if the sensor on your back door goes to ‘open’ status, it would trigger your tablet to announce “back door is open”. It can get far more interesting and complex if you’d like; it could, for example, announce that ‘open’ status every five minutes until the door closes. There are other Tasker plugins that allow all manner of things to occur. The Joao AutoApps in particular are awesome.