I am not sure about the question that you are trying to ask.
It will be a great help if you can elaborate this more.
What software that we are talking about here ?
I thought I was in a Lightroom software forum.
In Lightroom went to web tab then preview templates but nothing shows.
That is known as a Web module.
What is your exact workflow?
What is the version of Lightroom and also please share your system configuration.
Here is a tutorial of how to create a web gallery : https://helpx.adobe.com/lightroom/help/creating-web-galleries-basic-workflow.html
Make sure that you are doing the correct steps.