How to create custom template of Typo3 bootstrap_package

I am quite new in typo3. I read somewhere

You should never edit the original templates of an extension as those changes will vanish if you upgrade the extension

How to create my own custom template based on bootstrap_package extension? I would like to override some files in parital/layout. It would be great if someone can post like/tutorial. A folder structure and a simple custom typoscript that implement bootstrap_package for my custom temple would be great help.

The bootstrap package developers already added something for this. It is possible to set different locations, where templates are stored. It also uses a fallback solution, that means if a template is not found, it will fetch the original one from the extension.

Create a directory in the fileadmin directory, for example fileadmin/templates/BootstrapPackage. Inside this directory, create the directories "Templates", "Layouts" and "Partials".

In TYPO3 backend, go to the constant editor of the root page and select everything like the screenshot says:

Set the fields "Layout/Partial/Template Root Path" to your new created directorys (fileadmin/templates/BoostrapPackage/Layouts|Partials|Templates). Save and clear the cache.

Now you can create new templates. If you place an exacly named file like it is named in bootstrap_package/Resources/Private/(Layouts/Partials/Templates)/Page/ , TYPO3 will use the new template instead.