Add a new file using the Add Files button in Lightning Experience. You can upload a new file to a given library's folder/subfolder. After a file is created, you can view most of its metrics:
File details on Lightning Experience
There no such thing as tagging. Let's switch back to Salesforce Classic. You should already be familiar with switching to Salesforce Classic; just click on Switch to Salesforce Classic on your user's icon, as illustrated here:
Jump to the Salesforce Content tab and select the library and the ...
