The favicon of your TYPO3 Introduction Package web site is declared in the typoscript constants section of the "Introduction Package" template.

The favicon that comes with the Introduction Package looks like the orange TYPO3 logo.

If you wish to change the favicon to your own, then simply upload your favicon to your web server. You could upload it using the File manager in the backend, or you could put your favicon in an extension like I do.

Then just add the following into the constants section of your site template to tell the Introduction Package where to find your new favicon:

page.favicon.file = EXT:site_package_typo3hub/Resources/Public/Icons/favicon.ico

That example is for where I have this web site's favicon located in an extension.

If you have uploaded your favicon else where you would replace the part after the equals sign accordingly so that it points to your favicon "ico" file. So this is what it should look like if you uploaded your favicon to the fileadmin folder:

page.favicon.file =  fileadmin/MyFavicon.ico

And remember, this goes in the constants section of your site template.