How do I open a specific app in my shelf tabs?

You mean how do you put a specific App in the Shelf so you can use the shelf to launch it later?

What is the name of the App and in which tab of the shelf do you want to put it (you can only drag & drop new shortcuts into "regular" shelf tab types)?

Is one of your tabs in the default main shelf named "Apps" or have you already removed that tab from the main default shelf?

Thank you for your response. I figured out how to do what I wanted.